Recently, bed bugs appeared in my apartment.

Bed bugs (Cimex lectularius) are indoor pests belonging to the genus Cimex in the family Cordycepsidae, order Hemiptera. In Japan, they were once nearly extinct after World War II due to the widespread use of effective insecticides, but have begun to increase again since around 2000 due to the ban on the use of DDT and the increase in inbound tourism (Hirao, 2010).

I never imagined that I, someone who works with insects, would be bitten by bed bugs. In a way, it was fortunate that I was able to take many photos of bed bugs (?), but I was bitten 6 to 10 times every night on the backs of my hands, arms, and neck, and on top of that, I became ill and caught a cold, so it was a very painful experience.

Therefore, here I would like to summarize the ecology of bed bugs, along with my personal experience from their initial infestation to eradication, and refer to relevant literature.

In conclusion, there are limits to what you can do to get rid of them yourself, and if you want a quick solution, I think it's best to rely on a pest control company. Even I, who loves cleaning and lives a semi-minimalist lifestyle, felt that way, so I think there are probably no exceptions.

The reason is that while laundry and commercially available insecticides (excluding pyrethroids) are effective, liquid sprays or gaseous fumigations do not spread sufficiently throughout a real house with a lot of clutter, and since insecticides are ineffective against eggs, continuous pest control is necessary after hatching.

Depending on the company, many also use other methods such as high or low temperature insecticide application, sealing gaps, trapping, and visual inspection, resulting in a completely different level of service.

Contrary to what is advertised, the extermination costs are typically over 100,000 yen, which is quite expensive. However, considering the certainty and time saved, I believe it's well worth the payment.

I think self-extermination is only feasible for those who are prepared to fight for a long time.

This article summarizes a real-life experience review of bed bugs, from their discovery to eradication, along with information about their ecology.

The first sign of trouble: From bite marks and symptoms to realizing "it might be bed bugs."

The first physical abnormality I noticed

The first symptoms of bed bugs appeared in mid-April. After visiting a friend's house with a large group of people, I developed slightly itchy red spots around my wrists, and at first I thought it might be due to a viral cold. I had previously developed similar spots from a viral cold, and I actually developed chills and caught a cold afterward, so I was convinced that "this must be a cold caused by being with other people."

This cold lingered for quite a while, with persistent runny nose, cough, and sneezing, and even a loss of taste. Although tests showed it wasn't coronavirus or influenza, it worsened to the point where I developed cough-variant asthma even after recovering.

After recovering from my cold, my health improved somewhat, except for my cough-variant asthma. However, for some reason, the spots on my skin continued to increase rather than subside.

It was at this point that I finally started to think, "Could this possibly be caused by an insect rather than a cold...?"

This was because I had prior knowledge of the issue. During my graduate studies, I heard through someone that there was a lot of talk at the public health center about the increase in bed bugs, and I did some research on it myself.

Just in case, I lifted the mattress I always use and examined the mesh part, and found something very small wriggling. I picked it up with my usual tweezers and examined it with a stereomicroscope... and there it was. It was a bed bug.

I found it and even took a picture so easily, but in reality, it's not that simple.

The media often focuses on the adult form, which is large, brown, and relatively conspicuous. However, the first-instar larva, newly hatched from the egg, is only about 1.5 mm long, and only those with very keen eyesight can spot it against a white background. Most people would simply overlook it.

Even more cleverly, and this is a common characteristic among insects, bed bugs will stop moving when they sense they've been detected by vibrations or other means. Mammals, including humans, find it extremely difficult to spot stationary objects.

Furthermore, since most people don't have tweezers or a stereomicroscope, they probably wouldn't be able to catch a first-instar larva and definitively identify it as a bed bug.

In that respect, I think we were quite fortunate to have discovered it so early.

Most people would be wise to be suspicious based on the symptoms of bite marks.

Characteristics of bite marks and differences from tick bites

In the case of bed bugs, they primarily target the arms, legs, and neck, and unlike fleas, lice, mosquitoes, and ticks, the red bite spots often appear in a straight or zigzag pattern with 3 to 5 spots close together (Akhoundi et al., 2023). This pattern is sometimes called "breakfast, lunch, and dinner." However, since bed bugs are only active at night, this is merely a symbolic name.

There are various theories as to why this pattern occurs, so I will omit them here. For more details, please refer to Doggett et al. (2012).

The spots may become raised or turn into blisters, and the itchiness varies depending on the stage of larval development and individual differences, ranging from an itch as mild as a mosquito bite to an itchiness so severe that you can't help but scratch.

Because I was sleeping in long sleeves and long pants at the time, the area I was bitten in was limited, mainly the back of my hands, wrists, and the front of my neck. If you notice that exposed areas are being bitten regularly every morning, you can strongly suspect bed bugs. However, in my case, even though I was wearing long sleeves, they often managed to burrow into my forearms and up to my elbows and bite me.

Unfortunately, bed bugs are nocturnal and inject an anesthetic when they bite, like mosquitoes, so you rarely notice you've been bitten, and by morning they've hidden away in the shade, leaving almost no trace (Akhoundi et al., 2023).

Humans toss and turn in their sleep at night, and it seems like they could be crushed at any moment, but normally you never see bed bugs being crushed.

This is likely due to their high speed of movement and their extremely flattened shape. As someone who studied biology, I was impressed in a way, thinking, "Evolution is amazing!", but it can also be said that they have some troublesome characteristics.

The bite itself usually heals naturally within one to two weeks without treatment, so there is no need to worry (Akhoundi et al., 2023). There is currently no evidence that they transmit dangerous infections like mosquitoes.

Being bitten is very stressful, but try to stay calm, wash the bite with soap and water, and apply a topical steroid or antihistamine (Akhoundi et al., 2023). Scratching is the worst thing you can do. I didn't have a severe case, so I managed without medication. In Japan, I think it would be something like Lindelon Vs ointment or Muhi.

Ideally, I would recommend going to a hospital for an examination, but even then, there's no guarantee that there will be a doctor who is knowledgeable about bed bugs (Doggett et al., 2012). Ultimately, even if you decide to call a pest control company, you'll need to collect actual insects or take photographs as evidence. If you're unsure, I think it's more reliable to have a pest control company examine it directly rather than going to a hospital.

Where are they hiding in your house? A complete guide to finding bed bugs in your home.

Whether you're trying to get rid of bed bugs yourself or hiring someone to do it, the first step is to find out where the bed bugs are hiding during the day.

Hiding places indicated in the literature

Bed bugs tend to spread mainly in bedrooms because they feed on blood at night.

Studies have shown that within bedrooms, the incubation rates are 85% in beds, 52% in bedding, 37% in baseboards and carpets, 26% in furniture such as lamps and dressing tables, 25% in sofas and chairs, 14% in walls and ceilings, and 6% in clothing (Hirao, 2010).

In severe cases, they may enter electrical outlets, pipes, and air ducts, but this is rare (Delaunay, 2012). While there is a small possibility they could enter electrical appliances, this is usually uncommon and therefore a low priority.

Hiding places that were actually confirmed at home

Ultimately, what I was able to confirm with my own eyes was the inside of the mesh of the folding mattress, the top and middle of the curtain, the corner of the flooring between the mattress and the curtain, and the inside of the bench stool next to the mattress.

In other words, it was only found around the bed, and conversely, I didn't see it around the desk, kitchen, bathroom, or toilet. If I had left it as it was, it would have likely spread to other rooms.

Regarding bathrooms and shower rooms, bed bugs are vulnerable to water and have difficulty climbing on the smooth surfaces, making them less likely to enter (Delaunay, 2012).

First, I think it's best to thoroughly search around your bedding. The larvae are a yellowish-white color, and the adults are brown, so they can be difficult to spot depending on the background color, and the first-instar larvae are very small. Shining your phone's flashlight on them will make them easier to find.

Another sign is what's called bloody feces, which, horribly, can be found in the corners of a room, consisting of feces mixed with your digested blood. Check for this as well.

Bed bugs are related to stink bugs, and when they attack, they emit a sour odor. In severe cases, this odor may linger strongly (Delaunay, 2012).

First aid measures taken: Washing, drying, and cleaning

If you discover bed bugs, the first thing to do as emergency measures is to thoroughly wash, dry, and clean your home. This method has been noted in literature (Hirao, 2010). However, don't expect this to completely eliminate them.

The effects of washing and drying

Regarding washing, it has been confirmed that all adults, larvae, and eggs are killed by washing in 60°C water and tumble drying at 40°C or higher for at least 30 minutes, or by dry cleaning (Hirao, 2010).

This can be done in a home washing machine with a drum-type dryer or at a laundromat. While there is insufficient evidence for using only a dryer, bed bug exterminators recommended running it on a high setting for 40 minutes.

It is said that even regular room-temperature washing is effective against everything except the eggs, and when I washed curtains that couldn't be put in the dryer, I found the dried-up corpses of large bed bugs.

Vacuuming and sun drying in practice

Vacuuming is effective in reducing the number of bed bugs, as it not only sucks them up but also physically kills them with the force of the suction.

It has been confirmed that 97.4% of adult insects die within a week, and the remaining insects all die within eight days. It is also known that 100% of larvae die within one day (Tanaka & Tanaka, 2017).

However, since I only had a Swiffer-type mop, I couldn't expect this effect. I could see with the naked eye that the Swiffer-type mop was wiping away the larvae, but I think it's inferior to suction.

Sun-drying is also effective; it has been found that wrapping them in a black plastic bag and turning them over so that both sides are exposed to the sun can kill insects by reaching temperatures above 80°C, although this is quite a time-consuming process.

Attempting to exterminate pests yourself: The effectiveness and limitations of insecticide sprays.

However, simply washing, drying, and cleaning has its limits. In fact, it didn't make them go away.

So, although I was hesitant to use it if possible, I decided to try it out and used insecticide.

Ingredients and effects of commercially available insecticides

There are four types of active ingredients in commercially available insecticides used for bed bugs: pyrethroids, organophosphates, carbamates, and metadiamides (brofranilide).

However, even if major pyrethroid-based insecticides are labeled "effective against bed bugs!", they have little effect on bed bugs today. Specifically, this includes products like LEC's "Balsan One Touch Smoke Type" and Earth Pharmaceutical's "Medicinal Bed Bug Cockroach Earth."

The bed bugs that have reinvaded Japan have developed resistance to pyrethroid insecticides and are a population known as "super bed bugs." It's like a monstrous evolution, reminiscent of Doma from Demon Slayer, but such evolution actually occurs in many insects. It's an ability gained through the sacrifice of countless corpses, and is the result of natural selection (or artificial selection).

Actual experiments have shown that pyrethroid-based fumigants have a mortality rate of less than 30% even after 72 hours, and spray formulations have a mortality rate of less than 60% (Kurashima, 2024).

Organophosphates and carbamates have traditionally been effective, with a 100% eradication rate reported after three weeks (Muto, 2015).

However, bed bugs that have developed resistance to organophosphate and carbamate insecticides have now been identified both domestically and internationally, and it has been pointed out that these insecticides may become ineffective in the future (Suga, 2022). They may still be effective in 2026, but their effectiveness may decrease year by year.

Broflanilide is a new drug and can be used without problems for the time being. One study showed an eradication rate of 95% or higher after two weeks (Kurashima, 2024).

Therefore, always check the active ingredients on the label before purchasing insecticide. Many people are buying pyrethroid-based insecticides and suffering because they are ineffective.

The product I used this time was Earth Pharmaceutical's "Zerono Night Cockroach and Bed Bug Spray, 1-Push Type, 60 Uses".

This product contains broflanilide (brand name: Tenevenal) as its active ingredient.

I used this product for about a week, spraying three times into the air daily and three times on the areas where I had previously found bed bugs. The manufacturer recommends using less, so please proceed at your own risk.

As a result, I started seeing about 3 to 5 bed bugs in a near-death state every day. I think it played a role in steadily reducing their numbers.

While cleaning further, I discovered an adult insect in a near-death state, which is likely the parent of all the larvae that had entered the room!

While cleaning, I found several first-instar larvae on the quick wiper. Since wiping will wipe away the insecticide, be sure to spray it again after cleaning.

Other options include LEC's "Balsan Ambush Spray" (carbamate-based) and Earth Pharmaceutical's "Zerononight G Cockroach and Bed Bug Fumigation Agent for 6-8 Tatami Mats" (broflanilide). I haven't tried these myself, so they might be better depending on the situation.

Precautions when using insecticides

However, these drugs are not without risk to humans. Although it is unlikely to be these drugs, there have been deaths from bed bug pesticides overseas (Laborde-Castérot et al., 2024), and while these drugs are currently used after testing and deemed safe, there is no knowledge of long-term exposure, and the future is uncertain.

The insecticide DDT was once considered harmless and was misused as a "miracle drug." Bed bugs also saw a decline in numbers due to DDT (Akhoundi et al., 2023), and were nearly extinct in Japan. However, DDT has now been confirmed to be carcinogenic and is no longer used except in a very limited number of regions (Le Couteur & Burreson, 2003).

Remember that no medicine is completely harmless, and use it in moderation.

But it still doesn't go away... The recurrence revealed the "pitfalls of amateur pest control."

I combined several possible control methods, but to put it simply, I couldn't eradicate them on my own in about two weeks. Even after using insecticides, I continued to get bitten in multiple places every day.

There could be several possible causes.

The problem recurs after evacuating to a different location.

First, while washing and drying clothes and cleaning can reduce their numbers, if these aren't done simultaneously, bed bugs that have fled to another location will return to the same spot.

I actually washed my curtains and sheer curtains once, but after a while I started seeing bed bugs on them again. I couldn't dry them at a high temperature, so it's possible that eggs remained.

It's possible to get it to last if you wash it many times, but it requires a lot of patience.

Furthermore, there are parts that are impossible to wash, dry, or clean, no matter how hard you try, such as the inside of a mattress or an air conditioner. If they take refuge in those areas, there's nothing we can do.

Prolonged duration due to house structure and mass egg-laying

Regarding insecticides, the aforementioned claim of 100% eradication is merely the result of experiments. In reality, houses have complex layouts, and with a lot of furniture and other items, there are many gaps through which insects can enter, so they may not penetrate rooms so easily.

Furthermore, since people typically clean their homes frequently, the chemicals are wiped away. In fact, there is even a theory that the chemicals might be more effective in a dirty room (Kurashima, 2024).

Furthermore, the concentration of commercially available medications may be too low.

More importantly, these insecticides, which act on the insect nervous system, have virtually no effect on eggs that are immobile and protected by their shells. Experiments have shown that even when various insecticides are sprayed directly on the eggs, the survival rate exceeds 80% (Hinson et al., 2016).

Furthermore, a female bed bug lays an average of 131.9 to 155.7 eggs in her lifetime (Polanco et al., 2011c). Another study suggests 200 to 500 eggs (Akhoundi et al., 2023). She doesn't lay all of these eggs at once, but rather a few at a time after each blood-feeding, laying about five eggs per day.

Therefore, if, like me, the adult insects lay eggs in your room, even if the medication is effective against the hatched individuals, a long battle is inevitable.

I learned about professional pest control methods and typical costs by consulting with a pest control company.

Based on these results, I decided to hire a pest control company (extermination service).

The reason I decided to hire a professional was that, although the insecticide spray was effective, I felt it would prevent the situation from escalating and that I couldn't be sure it would completely eradicate the problem.

But the biggest deciding factor was when my parents told me, "We have pets, so please don't come back home until the bed bugs are gone" (laughs).

Bed bugs also opportunistically feed on the blood of pets. In other words, although it is not their primary food source like human blood, there is clear evidence that they feed on the blood of dogs, cats, rabbits, and birds such as chickens when the opportunity arises (Black et al., 2021).

I was originally supposed to attend a memorial service at my parents' house, but I couldn't go because of bed bugs. When I think about the risk of spreading bed bugs to other people and causing them trouble in the future, I think it was the right decision to hire a professional exterminator.

Costs and scope of work revealed in the estimate

I think it's best to get quotes from several companies. I requested quotes from two companies, a large corporation and a small to medium-sized enterprise.

While the large company responded quickly to my email, they provided an estimate without actually coming to my house to inspect the condition. In contrast, the small company came to my house the same day, inspected the condition, and prepared an estimate. As a result, although the small company's initial estimate was higher, I decided to go with them.

I want to believe that bed bug extermination is unlikely to be a complete failure, but I think it's worth considering not only the price, but also whether they are quick to act rather than just talk, whether they can actually find first-instar larvae in your home, and whether they advertise themselves as being good at bed bug extermination as well as general pest control.

While some companies advertise prices online as starting from 40,000 yen for a single-person apartment, you will almost certainly not get paid that price.

This is because a second extermination is almost certainly carried out two weeks after the first. This is a standard extermination method because, as mentioned above, the pesticide is ineffective while the eggs are still in the egg stage, so treatment is necessary after the eggs have hatched (Campbell & Miller, 2017). It takes 4 to 12 days for the eggs to hatch (Akhoundi et al., 2023). You should be wary of any company that doesn't follow this procedure.

It might seem like a gray-area advertisement that misleads customers, but even ordinary businesses do this (probably due to price competition), so it's probably best not to judge a business's quality based solely on its price.

I ultimately paid around 140,000 yen for the extermination, including the guarantee, but if you live alone, the price might be a bit lower. However, I compromised because I wanted it done quickly. In any case, I think it's guaranteed to cost over 100,000 yen.

Differences in pest control methods among different companies

Pest control methods vary from company to company. Some use only chemicals, while others combine various methods. If a company offers a guarantee period, any choice should be fine, but if you are hesitant about the use of chemicals, a company that advertises using minimal chemicals might be a better option.

The following are typical pest control methods used by pest control companies.

• Heat treatment: Kill insects with high-temperature steam.
• Cooling treatment: Kill insects with dry ice or similar methods.
• Vacuum treatment: Use a powerful vacuum cleaner to suck up the bed bugs.
• Chemical treatment: Applying chemicals. This often involves not only fumigation or spraying, but also applying liquids to the corners of the room.
• Sealing treatment: Seal small gaps in the corners of the room with a hardening resin.
• Capture and treatment: Place bed bug traps (bed bug traps) in the corners of the room to directly capture and kill them and prevent re-infestation.

Warranty periods vary from company to company, but they are often 3 months, 6 months, or 1 year from the second application.

Considering the life cycle of bed bugs, it takes 4 to 12 days for eggs to hatch (Akhoundi et al., 2023), and about 1.2 to 1.3 months for them to develop from egg to adult (Polanco et al., 2011a). Their life cycle is 2 months (Izri et al., 2020), so theoretically, 3 months might be sufficient.

However, there's always a possibility that they could be brought in from outside, or hidden in household items and accidentally emerge, stinging you again a few months later, so six months might be a safer timeframe.

Bed bugs are often said to be able to survive for over a year without feeding on blood on the internet, but one study showed that first-instar larvae live for an average of 13.8–36.3 days, and fifth-instar larvae and adults live for an average of 41.5–142.6 days, suggesting that this claim might be an exaggeration (Polanco et al., 2011b). Another study yielded similar results (Akhoundi et al., 2023).

If we take these numbers at face value, it seems unlikely that it will appear for at least six months.

The process leading up to the day of the pest control service and the number of days it took for complete eradication.

I think they can start the work within a few days. In my case, they inspected the site on the same day as my initial contact, and performed the first extermination five days later. I scheduled the second extermination two weeks later. So, it took 19 days from the initial contact to complete extermination, but I stopped getting bitten six days after the first extermination.

Preparation before construction

There may be things you need to do yourself before the day the contractor arrives.

In a common scenario, household items, excluding large furniture and appliances, must be bagged. This is to isolate bed bugs from the room. Bed bugs are thought to be unable to climb smooth plastic bags.

However, bed bugs are said to be able to break through thin plastic and get out, so you will need thick 30L or 45L transparent plastic bags that are at least 0.04mm thick. This task is quite difficult; it's almost like moving house.

These plastic bags aren't usually found in regular supermarkets, but you might be able to buy them at home improvement stores. I bought a pack of 30 45L transparent heavy-duty garbage bags (0.05mm thick) at Kohnan, but if you're willing to pay an extra fee, the service provider can provide them, so that's fine if you don't want to think about it too much. Some service providers might even include them in their plans from the start.

These bags cannot be returned until the second treatment, two weeks later, completes the extermination process. Therefore, be prepared to live with the bags for at least two weeks.

Furthermore, customers were encouraged to use coin laundries or dry cleaning services for clothing that can be washed and dried.

From here on, the methods used by the company I hired may differ depending on the company.

Details of the first and second construction phases

For the first treatment, the person in charge went out, and the aforementioned chemicals were applied and sprayed throughout the room, and gaps were sealed. I was told it would take about half a day, but in my case, since the room was small, it was finished in about 3 hours. That's the speed of a professional!

Backpacks and bags used when going out are also subject to pest control, but these were visually inspected and treated with insecticide. Bags containing frequently used items were also treated with insecticide at that time.

On the first night after the treatment, I felt like I was still being bitten in a few places, but when I returned home the following evening, I found three dead insects. I think the insecticide applied to the corners of the room had worked. I haven't been bitten since then.

For the second treatment, if bed bugs remain in the room, the work will be performed in the same room as the first treatment, but the bags will also be checked to ensure that no bed bugs remain.

I haven't had the second treatment done yet, so I'll report back once it's completed.

Measures to prevent recurrence and ensure it never happens again

Possible entry points

I still don't fully understand why bed bugs have appeared in my house.

Since bed bugs do not reproduce asexually, they must mate, making it unlikely that a single larva would enter a house and reproduce. The most likely scenario is that a mated adult bed bug entered the house.

I've only been able to find one female adult at home, so this is the pattern I'm considering for now. I started experiencing stinging symptoms around May, but the exterminator suggested that the insects probably entered the house around December.

However, there are many possible entry points, and we are unable to pinpoint a specific one.

Generally, outbreaks have been reported in all forms of accommodation and transportation, including hotels, trains, airplanes, and ships (Delaunay, 2012).

In my case, there are two possible scenarios.

One possibility is that I brought bed bugs back with me from my travel destination. I'm quite comfortable in small spaces, so I often use capsule hotels when traveling alone. However, there are many international tourists due to the inbound tourism trend, and I was careless, so adult bed bugs may have gotten into my backpack or jacket. I was staying at a capsule hotel in Tokyo around January. Checking the 'Bed Bugs Map Japan', it seems that there was a bed bug infestation there about two years ago.

Another possibility is that they got mixed in with a package. Because of my job, I have specimen samples sent to my home in cardboard boxes, and I also frequently make purchases online from Amazon and other retailers, so it's possible that adult bed bugs got mixed in with one of those packages.

Hotel and luggage measures

Are there any preventative measures that individuals can take? Regarding hotels, the following methods have been suggested in research (Delaunay, 2012; Hentley, et al., 2017).

• Upon arrival, use a flashlight to quickly check the bedding area, and if you find any suspicious signs, do not use that room.
  • Check the seams and piping of the mattress.
  • Check the corners of the bed frame.
  • Check the top of the curtain.
  • Check the gaps between pillows and sofas.
  • Black spots (blood and feces), bloodstains, eggs, and larvae were observed.
  • Since bed bugs are related to stink bugs, they emit a sour smell, so check for a strong odor.
• Place your belongings away from the bed (such as in the bathroom). Bed bugs are less likely to enter bathrooms and shower rooms because they are slippery, difficult to climb, and are vulnerable to water. If there are no other options, place them on a chair or similar object in the center of the room, away from the walls.
• Seal your belongings in a large plastic bag. Smooth plastic bags make it difficult for bed bugs to climb.
• For exposed skin, use mosquito repellent spray containing DEET. In Japan, examples include Earth Pharmaceutical's "Saratect."
• Sleep with clothes on. You're less likely to get bitten through fabric.
• Store your pajamas in a separate plastic bag.
• Don't leave worn clothes lying around. Experiments have shown that soiled clothing absorbs human odors, attracting bed bugs and providing them with a "foothold" for movement. Put clothes you've taken off into a plastic bag immediately.
• Upon returning home, immediately do the laundry, and wash or dry any suspected clothing at a high temperature. As mentioned above, this will kill the insects, including the eggs.
• Don't bring your suitcase straight into the house. Wash it in the bathroom if possible.

Another option is to avoid hotels that have a history of bed bug infestations. 'Bed Bugs Map Japan' compiles evidence-based bed bug sighting records on Google Maps (Bed Bugs Map Japan, 2026). While this may be helpful, along with the hotel's attitude towards bed bugs, it should only be used as a reference; there's still a good chance bed bugs could be found in hotels not listed.

However, even considering all of the above, I think it's difficult to implement a perfect intrusion prevention measure. While some hotels will properly exterminate the pests, there are also cases where they turn a blind eye, so a societal approach may be necessary.

The current price range for bed bug extermination makes it difficult for low-income individuals to afford it, which could lead to the spread of the infestation.

Once they get into your house, cleaning alone won't prevent them from breeding. I have very few possessions and I clean fairly often because I like it, but they still breed in my house.

Summary: Early detection and correct diagnosis are key when it comes to bed bugs.

Naturally, bed bugs grow the more blood they suck.

If left unattended, a single female can lay approximately 5 eggs per day, averaging 131.9 to 155.7 eggs in a room, and if it's in your own private room, these offspring will be raised solely on your blood.

These insects will never disappear even if left unchecked; in fact, they can even inbreed, allowing the next generation to grow (Fountain et al., 2014). Studies have shown that colonies can be founded by a single adult female, and that their genetic diversity is extremely low.

If there is no pest control and the population has a normal food supply, the number of eggs and larvae will increase exponentially. Even under the harsh assumption of starvation where females do not lay eggs daily, simulations show that the population doubles every 13 days (Polanco et al., 2011a).

At first, you might dismiss it as something like a mosquito bite, but once they grow into adults, their numbers multiply exponentially (like rats), and it becomes impossible to control.

Let's take some measures before that happens.

The best option is to hire a reputable pest control company, but if that's not possible, be sure to use multiple methods, such as washing and drying clothes, using a vacuum cleaner, and using insecticides other than pyrethroids.

I hope this article will be of some help to those suffering from bed bug infestations.

References

Akhoundi, M., Zumelzu, C., Sereno, D., Marteau, A., Brun, S., Jan, J., & Izri, A. (2023). Bed bugs (Hemiptera, Cimicidae): a global challenge for public health and control management. Diagnostics, 13 (13), 2281. https://doi.org/10.3390/diagnostics13132281

Bed Bugs Map Japan. (2026, May 17). Bed Bugs Map Japan. https://bedbugsmapjapan.com/

Black, MK, Chandler, JG, Trout Fryxell, RT, & Vail, KM (2021). The Common Bed Bug (Hemiptera: Cimicidae) Does Not Commonly Use Canines and Felines as a Host in Low-Income, High-Rise Apartments. Journal of Medical Entomology, 58 (6), 2040-2046. https://doi.org/10.1093/jme/tjab070

Campbell, BE, & Miller, DM (2017). A method for evaluating insecticide efficacy against bed bug, Cimex lectularius, eggs and first instars. Journal of Visualized Experiments: JoVE, 121, 55092. https://doi.org/10.3791/55092

Delaunay, P. (2012). Human travel and traveling bedbugs. Journal of Travel Medicine, 19 (6), 373-379. https://doi.org/10.1111/j.1708-8305.2012.00653.x

Doggett, SL, Dwyer, DE, Peñas, PF, & Russell, RC (2012). Bed bugs: clinical relevance and control options. Clinical Microbiology Reviews, 25 (1), 164-192. https://doi.org/10.1128/CMR.05015-11

Fountain, T., Duvaux, L., Horsburgh, G., Reinhardt, K., & Butlin, RK (2014). Human-facilitated metapopulation dynamics in an emerging pest species, Cimex lectularius. Molecular Ecology, 23 (5), 1071-1084. https://doi.org/10.1111/mec.12673

Hentley, WT, Webster, B., Evison, SE, & Siva-Jothy, MT (2017). Bed bug aggregation on dirty laundry: a mechanism for passive dispersal. Scientific Reports, 7 (1), 11668. https://doi.org/10.1038/s41598-017-11850-5

Hinson, KR, Benson, EP, Zungoli, PA, Bridges Jr, WC, & Ellis, BR (2016). Egg Hatch Rate and Nymphal Survival of the Bed Bug (Hemiptera: Cimicidae) After Exposure toInsecticide Sprays. Journal of Economic Entomology, 109 (6), 2495-2499. https://doi.org/10.1093/jee/tow223

Hirao, Soichi. (2010). The resurgence of bed bugs and the current status of control efforts. Journal of Sanitary Zoology, 61 (3), 211-221. https://doi.org/10.7601/mez.61.211

Izri, A., & Parola, P. (2020). Bedbugs. New England Journal of Medicine, 382 (23), 2230-2237. https://doi.org/10.1056/NEJMcp1905840

Sugama, Toru. (2022). Search for novel insecticidal components against organophosphate-resistant bed bugs. Bulletin of the Japan Environmental Sanitation Center, 49, 4. ISSN: 0389-0805, https://www.jesc.or.jp/Portals/0/center/library/shoho/2021shoho4.pdf

Komagata, Osamu. (2024). Basic characteristics of bed bugs. Life and Environment, 69 (2), 4-8. https://www.jesc.or.jp/Portals/0/center/library/seikatsutokankyo/202403_Komagata.pdf

Komatsu, Kenji & Nakamura, Harumi. (2023). Survey of the habitat of tropical bed bugs and other bed bugs in Japan from 2019 to 2021. Journal of Sanitary Zoology, 74(4), 157-160. https://doi.org/10.7601/mez.74.157

Kurashima, Yuki. (2024). Practical evaluation of the novel insecticide component brofuranilide against bed bugs. Insecticide Research Group Handbook, 94, 10-16. https://www.jsmez.org/wp-content/uploads/2024/09/2024_94.pdf

Laborde-Castérot, H., Vodovar, D., Ortiz De Zevallos, A., Caré, W., Nisse, P., Bargel, S., … & Langrand, J. (2024). Trends in poisoning associated with the use of insecticides for bed bug infestations: a 20-year retrospective study in France. Scientific Reports, 14 (1), 16868. https://doi.org/10.1038/s41598-024-67727-x

Le Couteur, PC, & Burreson, J. (2003). Napoleon's buttons: How 17 molecules changed history. Tarcher. ISBN: 9781585422203 [=(2011). Spices, explosives, pharmaceuticals—17 chemicals that changed world history. Chuokoron-Shinsha. ISBN: 9784120043079]

Muto, Atsuhiko. (2015). Bed bugs and their effective control methods. Ministry of Health, Labour and Welfare. https://www.mhlw.go.jp/content/10900000/001332555.pdf

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Tanaka, Toyokazu & Tanaka, Toshio. (2017). Insecticidal effects on bed bug bodies and eggs by vacuum cleaners and dry ice treatment. Pestology, 32 (2), 63-67. https://doi.org/10.24486/pestology.32.2_63

In Japan, except in some regions, eating insects is extremely rare, and it can be said that it is almost unheard of among the younger generation, especially in urban areas.

While some advocate for eating insects to prepare for food shortages, cries of "Absolutely not!" are heard, mainly on social media. Even though I work with insects, I also feel a sense of pity for them and have reservations about eating them.

That being said, the truth is that, unintentionally, Japanese people eat insects (or components extracted from them) every day. Representative examples include cochineal, which contains carminic acid produced by the cochineal insect, and shellac, which is made by heat treatment or solvent extraction of lac, produced by the lac insect.

To put it simply, cochineal is used as a pure dye in food and cosmetics, lac is used as a dye in food, and shellac is used as a wax in many applications such as adhesives, food polishing agents, wood finishes, and SP records.

Cochineal is generally safe, but it's important to be aware that in rare cases, people who regularly use cosmetics containing cochineal may experience allergic reactions.

The reason cochineal continues to be used despite containing insects is likely because safe and inexpensive artificial colorings have yet to be found.

This article will explain cochineal insects and lac insects, as well as the components they produce.

What is the difference between cochineal insects and lac insects?

First, let's clarify the differences between cochineal insects and lac insects, which are often confused.

The cochineal insect (also known as the cochineal insect), Dactylopius coccus, belongs to the family Dactylopiidae within the superfamily Coccoidea and is distributed from the southwestern United States through Mexico to the temperate regions of South America (Schowalter, 2025). It is now sometimes cultivated in China. It uses prickly pear cacti (Cactaceae) as its host, inserting its stylets into the phloem tubes (tubes that transport sugars produced by photosynthesis throughout the plant) and feeding on the phloem sap.

On the other hand, the lac insect Kerria lacca (Laccifer lacca is a synonym) is classified in the family Kerriidae within the superfamily Coccoidea and is distributed in China, South Asia (India, Pakistan, Bangladesh), and Southeast Asia (Indonesia, Vietnam, Laos, Myanmar) (Watanabe, 2003; Takekawa, 2010; Bashir et al., 2022). Its hosts are extremely diverse, with over 400 plant species reported worldwide, but commercially, three species are used: Butea monosperma (Fabaceae), Schleichera oleosa (Sapindaceae), and Ziziphus mauritiana (Rhamnaceae). Like the lac insect, it lives by inserting its stylets into the phloem tubes and feeding on the phloem sap.

Although they both cling to plants in a similar way, cochineal insects are originally from the Americas, while lac insects are found in Eurasia. You can see that the plants they utilize and their habitats are completely different.

The components produced are also different.

Cochineal insects produce carminic acid, which is both a defensive substance and a pigment, while lac insects produce a waxy substance called lac, which contains laccaic acid as a pigment.

Why did the cochineal insect evolve to produce carminic acid?

It is believed that carminic acid was originally secreted by the cochineal insect to protect itself from carnivorous insects such as ants, ladybugs, and lacewings, as well as microorganisms (Schowalter, 2025). The defense provided by carminic acid is strong, and very few species prey on it.

However, some insects are known to still prey on cochineal insects. The larvae of the carnivorous moth Laetilia coccidivora, a member of the Pyralidae family, are known to prey on cochineal insects by spitting out a sac containing carminic acid. However, even in this case, their survival rate, development rate, and reproduction rate are significantly worse than when they feed on cochineal insects that do not contain carminic acid.

While carminic acid is merely a pigment for humans, it is actually an important component for cochineal insects.

The fact that cochineal insects themselves can turn red is thought to be due to carminic acid, and it is possible that this is an "honest signal" warning color, intended to convey "the redder, the more poisonous!" by possessing both pigment and defense properties, but this has not been thoroughly investigated. Examples of warning colors that serve as honest signals by combining pigment and antioxidant properties are well known (Blount et al., 2009).

What are the differences in the uses of cochineal lac and shellac?

Cochineal insects are killed with boiling water and dried to produce "black cochineal," and crushing black cochineal yields "cochineal," which contains carminic acid. For dyeing purposes, carminic acid is further chemically reacted to synthesize "carmine" (Akiyama & Sugimoto, 2014; Schowalter, 2025).

On the other hand, the lac produced by the lac insect initially clumps together on the branches of the host plant, but the lac removed from the branch is called "stick lac" (Toko and Komashiro, 2007). This stick lac can be washed and dried to produce what is called "seed lac," and further heat treatment or solvent extraction can produce "shellac," a pure wax that does not contain insect remains and has reduced or eliminated laccaic acid.

It's important to note that rack and shellac are different things.

How do these ultimately produced ingredients differ in their uses?

To put it simply, cochineal is used as a pure dye in food and cosmetics, lac is used as a dye in food, and shellac is used as a wax in many applications such as adhesives, food polishing agents, wood finishes, and SP records.

Because cochineal produces a vibrant red color, it was originally used for dyeing cloth, and there are records of its use in Central and South America from at least 600 AD (Schowalter, 2025). When Columbus visited the Americas during the Age of Discovery, it was highly valued by European nobility because of its superior strength and durability compared to older dyes, and it eventually became inexpensive and spread throughout the world. It was also introduced to Japan through trade with the West during the Momoyama and Edo periods, and was used by Sengoku warlords (Toko and Komashiro, 2007). However, with the advent of aniline dyes, its use for dyeing cloth declined, and other uses were developed.

In Japan today, cochineal is used as a food coloring agent in soft drinks, strawberry milk, alcohol, shaved ice syrup, confectionery, ham, sausages, and fish cakes, as well as in cosmetics such as lipstick, lip balm, blush, eyeshadow, and nail polish, and in art supplies. Note that in Japan, the cochineal used in food products is carminic acid, while in cosmetics it is carmine (Inomata, 2025).

Lac still contains a lot of laccaic acid, so it is used as a fabric dye and is known as lac dyeing (purple mineral dyeing) (Takekawa, 2010). Around 2000 BC, it was used in China and India as a dye and as a medicine called myrrh (traditional Chinese medicine). It had already been introduced to Japan during the Nara period and has been found in the Shōsōin Treasury (Toko and Komashiro, 2007). However, its use declined with the advent of aniline dyes and Western medicine.

In modern Japan, lac is added to food products and used to color sweets, bean paste, bacon, sausages, noodles, processed seafood, and jams.

Shellac was originally used as a finishing material because of its excellent properties for protecting and polishing wood. However, in the early 20th century, the developing electrical industry recognized its excellent properties as an electrical insulator, leading to increased demand. However, in 1907, when American Leo Baekeland invented Bakelite as a substitute, its use in that application declined (Le Couteur & Burreson, 2003).

However, shellac's other uses have expanded in many directions, and in Japan today it is used in countless ways, including paints, adhesives, varnishes for stringed instruments and wooden furniture, granular chocolates and gums that don't stain hands, pharmaceutical tablets, a coating agent for roasted chestnuts, and SP records (Takekawa, 2010).

These insects have truly been supporting society from ancient times to the present day, constantly changing their form along the way.

Do Japanese people really eat cochineal insects? From the cultivation of cochineal insects to their eventual appearance on the dinner table as a food coloring agent.

Some people might wonder, "Do Japanese people actually eat cochineal insects?"

In other words, regardless of whether cochineal is used, the point is that it's merely an extracted chemical component, and not the cochineal insect itself. (Some people might find that off-putting, though...)

Unfortunately (?), we can proudly say that the Japanese eat scale insects (Akiyama & Sugimoto, 2014; Schowalter, 2025).

Cochineal insects harvested from prickly pear cacti are killed by soaking them in hot water or exposing them to sunlight or heat, and then dried for preservation until they reach approximately 301 TP3T of their raw weight. This is "black cochineal."

The powder produced by crushing black cochineal is called "cochineal." Approximately 70,000 insects are needed to produce one pound (0.45 kilograms) of cochineal dye (Miller, 2022).

When cochineal is boiled in ammonia water or sodium carbonate solution and alum is added, a red aluminum carminate precipitate forms. This aluminum carminate is "carmine."

Furthermore, by adding other ingredients such as tin chloride, citric acid, borax, and lime, you can create a variety of colors ranging from pink to purple.

In other words, it's almost certain that whole insects are being crushed and then applied to or incorporated into food and cosmetics.

On the other hand, while lac insect lacs also contain insect bodies, shellac consists almost entirely of its chemical components.

Are cochineal scale insects disgusting?

Whether or not cochineal insects are considered disgusting is, of course, subjective, but there are several factors that contribute to that perception.

First, scale insects typically infest leaves in dense clusters and produce a cottony waxy substance. This is thought to protect against moisture loss, excessive sunlight exposure, and predators such as ants, but it is what makes the leaves look unsightly.

Furthermore, in order to excrete the excess sugar absorbed through the phloem (and also as a reward for ants guarding them), the plant "urinates" (diabetes), which gets on the leaves, creating a sticky, viscous substance, and weakening the plant itself, resulting in an even dirtier appearance.

But eccentric people like me think, "It's so small and cute!"

Furthermore, you could say that it's thanks to scale insects that you can put on makeup while enjoying red drinks and sweets like macarons, and then take and post sparkling, "Instagrammable" photos on social media like Instagram.

Therefore, rather than simply dismissing them as "disgusting," I think it's not a bad idea to show gratitude and respect to those who provide us with food. It's certainly not a pleasant experience for the cochineal insects themselves, who are the ones being eaten. (Although, there's also the perspective that they are being bred and thus the species is surviving as a result.)

While it may evoke a physiological aversion, insects and cosmetics are surprisingly closely related, as evidenced by the use of galls (five-grain galls, sumac ear galls) of the sumac aphid Schlechtendalia chinensis for teeth blackening in Japanese history (Ezure et al., 1987).

What are the dangers of cochineal? Does it cause allergies?

However, there is also the practical problem of cochineal insects: the existence of allergies (Akiyama & Sugimoto, 2014; Inomata, 2025).

There are multiple patterns of cochineal allergies.

The first type is occupational inhalation exposure, where workers who are routinely exposed to cochineal dye or carmine through inhalation, such as those engaged in extracting dye from cochineal insects or handling carmine in cosmetics factories, develop allergies.

The second type is those who exhibit skin symptoms caused by cosmetics containing cochineal.

The third type is caused by oral ingestion of foods containing cochineal.

The worst-case scenario is a combination of the second and third types, where applying cosmetics containing cochineal to the face causes the immune system to mistakenly perceive the cosmetic as a "foreign substance that attacks the human body!" and memorize its molecular structure (immunological memory). The next time food containing cochineal is consumed, the immune system overreacts and attacks the body itself. This is called "anaphylactic shock."

Many researchers believe that the cause of this reaction is not carmine from cochineal, but rather residual proteins derived from the body fluids of the cochineal insect that are involved in the manifestation of IgE-mediated allergic symptoms. However, there are also reports of reactions to carmine, so there are various theories.

It is believed that this system originally evolved to react to parasites (Palm et al, 2012). In other words, if a protein is the cause, then this can be rephrased as a reaction that occurs because our bodies mistakenly identify cosmetics containing cochineal insect fluid as "parasites!"

While this may sound quite frightening, despite its widespread use, only 22 cases have been reported in Japan since it began to be documented in academic papers in Japan until 2018, and there have been no deaths (Takeo et al., 2018).

However, it's possible that the lack of awareness is the reason why this condition is occurring more frequently than it actually is, so if you feel anything unusual, be sure to consult a doctor.

Why is cochineal still being used?

Why is cochineal, which is considered "disgusting" and potentially causes allergic reactions, still being used?

In fact, there was a period when artificial red coloring was used, but from around the 1970s, reports on the relationship between coloring and hyperactivity in children, as well as cell and animal studies suggesting that certain dyes may increase the risk of cancer, began to emerge, and health concerns about these synthetic dyes started to grow (Miller, 2022).

These concerns ultimately led to the banning of some dyes, such as Red No. 2 and Red No. 4. However, some of these harmful effects were later revoked.

As a result, naturally derived colorants such as carminic acid have begun to gain popularity.

Natural colorants have a very long history, which can be considered to guarantee their safety to some extent. Furthermore, because the manufacturing process is already established, it is possible to produce them at a lower cost, both in terms of time and money.

However, in addition to the reasons mentioned above, there is a growing number of vegans, vegetarians, and animal rights activists in the United States who do not want to accidentally consume insect-derived products.

Furthermore, using large quantities of prickly pear cacti does not necessarily result in good production efficiency.

Therefore, methods for artificial synthesis are being researched, but practical application is still some time away.

References

Akiyama, Hiroshi & Sugimoto, Naoki. 2014. Food allergies caused by cochineal dye and carmine intake. Pharmacia 50(6): 522-527. https://doi.org/10.14894/faruawpsj.50.6_522

Bashir, NH, Chen, H., Munir, S., Wang, W., Chen, H., Sima, YK, & An, J. 2022. Unraveling the role of lac insects in providing natural industrial products. Insects 13(12): 1117. https://doi.org/10.3390/insects13121117

Blount, JD, Speed, MP, Ruxton, GD, & Stephens, PA 2009. Warning displays may function as honest signals of toxicity. Proceedings of the Royal Society B: Biological Sciences 276(1658): 871-877. https://doi.org/10.1098/rspb.2008.1407

Ezure, T., Katsura, K., Ten, M., Taguchi, H., Ikeda, M., Matsuzaki, A., & Suzuki, T. 1987. Concept and Case Reports of Ohaguro (Teeth Blackening). Iwate Medical University Dental Journal 12(2): 217-221. https://doi.org/10.20663/iwateshigakukaishi.12.2_217

Inomata, Naoko. 2025. Cochineal dye allergy. Allergy 74(3): 174-176. https://doi.org/10.15036/arerugi.74.174

Le Couteur, PC, & Burreson, J. 2003. Napoleon's buttons: How 17 molecules changed history. Tarcher, 384pp. ISBN: 9781585422203 [=2011. Spices, explosives, pharmaceuticals—17 chemical substances that changed world history. Chuokoron-Shinsha, Tokyo. 368pp. ISBN: 9784120043079]

Miller, BJ 2022. Cochineal, a red dye from bugs, moves to the lab. Knowable Magazine. ISSN: 2575-4459, https://doi.org/10.1146/knowable-032522-1

Palm, NW, Rosenstein, RK, & Medzhitov, R. 2012. Allergic host defences. Nature 484(7395): 465-472. https://doi.org/10.1038/nature11047

Schowalter, TD 2025. Ecology, use, and management of cochineal insects (Hemiptera: Dactylopiidae). Journal of Integrated Pest Management 16(1): pmaf033. https://doi.org/10.1093/jipm/pmaf033

Takekawa, Yukiko. 2010. The Use of Shellac, a Natural Resinous Substance: Focusing on Shōsōin Treasures and Medicinal Properties. Osaka Science Museum Research Report 20: 65-70. https://www.sci-museum.jp/wp-content/themes/scimuseum2021/pdf/study/research/2010/pb20_065-070.pdf

Takeo, N., Nakamura, M., Nakayama, S., Okamoto, O., Sugimoto, N., Sugiura, S., … & Matsunaga, K. 2018. Cochineal dye-induced immediate allergy: review of Japanese cases and proposed new diagnostic chart. Allergology International 67(4): 496-505. https://doi.org/10.1016/j.alit.2018.02.012

Toko, Yukiko & Komashiro, Motoko. 2007. Natural red dyes. Journal of Life Engineering Research 9(1): 136-139. http://hdl.handle.net/10083/3267

Watanabe, Hiroyuki. 2003. Scale insects save tropical forests. Tokai University Press, Hadano. 136pp. ISBN: 9784486016182

When you go to a yakiniku (Japanese barbecue) restaurant, you may come across four parts of the cow's stomach (fore-stomach) as a type of offal: mino, hachinosu, senmai, and giara.

Because it has a distinctive taste and is a type of offal, it's a love-it-or-hate-it kind of dish, but some people enjoy eating it because of its crunchy texture and how well it pairs with alcohol.

If you only eat them, you might not think much about their true nature or role, but they actually play an important role for ruminants, including cows.

This is essential knowledge for anyone involved in livestock farming, and it wouldn't hurt for the general public to know it as common sense.

However, the stomachs of ruminants have an overwhelming number of names, and I often find it difficult to understand the correspondence between their function and shape.

However, regardless of the sheer number of names, a closer examination reveals that the form, function, and order of these elements are highly logical and inevitable.

Here, I'll summarize some simple ways to remember the names and morphologies of the stomachs of ruminants.

To put it simply, the process is as follows: tripe (fermentation) → honeycomb tripe (separation) → omasum (absorption) → abomasum (digestion).

What is rumination? Why do animals ruminate and have a forestomach?

Rumination is the act of bringing grass that has been swallowed back into the mouth and chewing it again.

If you observe cows, you'll notice them constantly chewing for extended periods. This is because their stomachs are regurgitating food they've already swallowed, and they're chewing it again.

While this behavior may seem a little unpleasant to humans, it is an adaptation that gives herbivorous ruminants a significant advantage in grasslands.

The grass that is regurgitated does not simply return to the mouth as is. Ruminants have a stomach divided into four compartments, and the first stomach (the rumen) houses microorganisms, which ferment the grass they eat. Furthermore, the regurgitated grass is not exposed to stomach acid.

The plant cell walls containing polysaccharides such as cellulose and hemicellulose found in grass are extremely strong and normally only partially digestible by the digestive capabilities of ordinary animals. However, ruminants produce volatile fatty acids (VFAs, such as acetic acid, propionic acid, and butyric acid) through fermentation, which serve as a source of nutrition (Mackie, 2002; Bao et al., 2019).

However, microorganisms cannot properly ferment large pieces of grass. Therefore, ruminants repeatedly bring the grass back into their mouths, physically destroying it with their teeth and thus assisting microbial fermentation (Matsuda et al., 2011).

This allows them to efficiently obtain nutrients from even small amounts of grass, surpassing other mammals (Hofmann, 1989).

Furthermore, while microorganisms themselves synthesize proteins for their own use, ruminants send urea from their food and urea synthesized in their liver to their first stomach, allowing microorganisms to synthesize proteins, which the ruminants then swallow, making them their own proteins (Hailemariam et al., 2021).

Furthermore, it has been pointed out that stomach microorganisms can break down some plant secondary metabolites (phenols, alkaloids, etc.), which helps broaden their diet and increase their tolerance to toxicity (Loh et al., 2020).

While this may seem like a highly efficient function, it is a function completely specialized for herbivores. For frugivorous, carnivorous, or omnivorous animals, it lacks flexibility and is not cost-effective to maintain such a voluminous stomach (a trade-off). Therefore, humans and pigs do not have such stomachs.

What are the different types of ruminants?

Academically, "true ruminants" (Ruminantia), which have four stomachs (quadriventricular stomachs), refer to animals belonging to the suborder Ruminantia of the order Artiodactyla. The suborder Ruminantia is divided into two suborders, the infraorder Machodea and the infraorder Euruminantia, and six families, with approximately 200 extant species (Bao et al., 2019). The major families and representative examples are as follows:

• Bovidae: Includes genera such as cattle, sheep, goats, antelopes, and antelopes.
• Family Cervidae: Includes genera such as deer (Japanese deer), moose, and reindeer.
• Family Giraffidae: Giraffes and okapis.
• Pronghorn family (Antilocapridae): Pronghorn.
• Family Moschidae: Includes the genus *Musk deer*, etc.
• Family Tragulidae: Includes the genus Tragulidae, etc.

However, there are other animals that perform rumination (chewing the cud) and foregut fermentation, even though they do not have a four-chambered stomach. These animals have evolved convergently from different lineages and are therefore not usually considered "ruminants." Compared to ruminants, they have simpler stomachs and are less efficient at absorbing nutrients from grass.

The Camelidae family (camels, llamas, alpacas, etc.) belongs to the order Cetartiodactyla, but is part of the suborder Neopoda (cameloid suborder). They generally perform digestion that is "similar to rumination," but their stomach has three chambers and lacks the absorption function of the third stomach (lobular stomach) in ruminants (Fowler, 2008). They evolved separately from the ruminant suborder.

Although hippopotamuses belong to the order Cetartiodactyla, they are closely related to whales as they belong to the order Cetacea-Hippomorpha, and while they do not ruminate, they perform forestomach fermentation, which involves microbial fermentation in the forestomach (Clauss et al., 2004).

Many large marsupials (e.g., red kangaroos, large Australian macropods) perform foregum fermentation in the foregum, but do not engage in rumination in the usual sense (regular, repetitive re-chewing) (Vendl et al., 2017). However, there are individual records of regurgitation and re-chewing, which is called pseudo-rumination or merycism. Merycism is much shorter and less consistent than rumination, and is therefore often distinguished from rumination.

The proboscis monkey, Nasalis larvatus, also feeds on leaves and fruits and performs mericism and foregum fermentation (Matsuda et al., 2011).

The hoazin (Opisthocomus hoazin) is a bird, but it is a very unique example of a bird that performs strong microbial fermentation in an enlarged foregum (crop). Its chemical fermentation products (volatile fatty acids) and microbial communities are similar to those of mammals that ferment their foregums, but it does not ruminate (Grajal, 1995). It has been reported that it feeds its offspring substances that have been partially broken down and fermented from its food.

List of names and functions of the stomachs (fore-stomachs) of ruminants

Below is a table summarizing the naming of ruminant stomach parts based on their order, appearance, and their roles in relation to grilled meat.

It can be seen that fermentation, separation, absorption, and digestion occur from the first to the fourth stomach.

How do you remember the name and function of the first stomach (rumen, tumor, or stomach tumor)?

The first stomach is called a tumorous stomach in terms of its appearance, tripe in yakiniku (Japanese barbecue), and rumen in English.

The most distinctive feature of the first stomach is its significantly enlarged, lumpy appearance compared to the other stomach parts, which is why it is called a tumor stomach.

The name "mino" in yakiniku (Japanese barbecue) comes from the fact that when it's opened up, it resembles a "straw raincoat" (mino).

This morphology is closely related to the role of the first stomach.

The first stomach contains microorganisms (bacteria, protozoa, archaea, and fungi) that ferment cellulose and starch, producing volatile fatty acids (VFAs; acetic acid, propionic acid, and butyric acid). VFAs are the main energy source, and the microorganisms also supply proteins and vitamins (Perez et al., 2024). Lumen gas is expelled through movement (stirring) and belching (eructation).

In other words, it is thought that the first stomach is specially enlarged, like a "bump" or "skin," to expand the habitat for fermentation-promoting microorganisms.

Furthermore, numerous papillae develop on the inner surface of the rumen, increasing the surface area and aiding in VFA absorption (Pokhrel & Jiang, 2024).

The English word "rumen" is borrowed from the Latin word "rūmen." While there are several theories about its etymology, it is generally believed to originate from the Proto-Italic *roug(s)mən ~ *rug(s)mən < Proto-Indo-European *h₁rewg-, *h₁rewǵ- "to burp" (Wiktionary contributors, 2026).

This name also accurately describes the role of the rumen, where methane is mainly produced by the reduction of hydrogen (H₂) and methylated compounds by methanogenic archaea. This generates rumen gas, which mainly consists of carbon dioxide (CO₂) 45-75% and methane (CH₄) 20-35%, and ruminants expel this gas by belching (Zhang et al., 2020).

While burps containing methane from cows are sometimes considered a problem due to their role as greenhouse gases, this can be attributed to the rumen (first stomach).

The first stomach can be easily remembered if you think of it as a lumpy, cloven structure that houses microorganisms and is where unnecessary burps are produced.

As mentioned above, microorganisms also play a role in protein synthesis and detoxification of plant secondary metabolites (phenols, alkaloids, etc.).

How can you remember the name and function of the second stomach (reticulum, honeycomb tripe, or stomach cavity)?

The second stomach is called the reticulum in English, while the tripe is called honeycomb tripe in grilled meat.

The terms "reticulous stomach" and "honeycomb stomach" come from the fact that the mucous membrane of the stomach lining is arranged in a hexagonal, honeycomb-like pattern.

The English word "reticulum" is borrowed from the Latin word "rēticulum," meaning "net," and derives from the Latin word "rēte" ("net, snare") + -culum (diminutive suffix) < Proto-Italic *rēti- < Proto-Indo-European *h₁reh₁- meaning "separate, loose." It is cognate with the English word "reticle," which refers to the aiming line on a gun scope or microscope (Wiktionary contributors, 2026).

In other words, all of these originate from the fact that they have a polygonal, network-like structure.

This morphology is also deeply related to the role of the second stomach.

The second stomach contracts to separate small particles and the liquid phase and send them to the next passage, while sending back larger particles for rumination (re-chewing) (Song et al, 2024). The rumen and reticulum function in conjunction and are collectively called the "reticulorumen" or "ruminoreticulum."

During this sorting process, the multi-chambered spatial arrangement created by the pillars, which are sometimes called honeycomb or mesh-like structures, acts like a "shallow cage," controlling the flow rate and sorting efficiency.

In other words, larger particles remain inside the basket and are returned to the first stomach, while smaller particles and liquids flow to the third stomach and beyond. Conversely, digestive function is minimal.

Due to these characteristics, foreign objects such as metal can easily become lodged, which can lead to a disease called wound reticulogastroperitonitis (hardware disease), especially in cattle.

The second stomach is easier to remember if you think of it as an organ that sorts out food that needs to be ruminated, with a honeycomb-like network structure.

How do you remember the name and function of the third stomach (lobe stomach, omason)?

The third stomach is called "leaf stomach" in terms of its appearance, "senmai" in yakiniku (grilled meat), and "omason" in English.

The term "leaf stomach" comes from its structure, which consists of many layers of folds (thin, plate-like tissues) that resemble leaves or petals. The term "double-leaf stomach" is similar.

The name "senmai" is said to originate from its appearance, which looks like it has "a thousand" folds overlapping inside. There is also a theory that it comes from the Korean word "jeonyeob" (千葉/千枚), but the meaning is roughly the same.

In other words, they stem from almost the same characteristics.

This morphology is also deeply related to the role of the third stomach.

The third stomach absorbs water, electrolytes, and some VFAs, increasing the solid content ratio of the digested food before sending it to the fourth stomach. It can be said that it removes liquid and separates even finer particles (Pérez et al., 2023).

At this time, a large absorption surface is created by numerous leaves (laminae), enabling efficient absorption of water and VFAs.

The third stomach is easier to remember if you think of it as having countless leaf-like folds that appear to be thousands of leaves, and that it absorbs the liquid portion before the intestines.

The word omasum is a loanword from the Latin omāsum, meaning "bull's stomach." The Latin word is thought to be derived from Gaulish, which in turn was borrowed from Carthaginian, which in turn is thought to be derived from the Proto-Semitic *ḥamṯ- meaning "abdomen" (Wiktionary contributors, 2026).

The meaning of "Omason" has changed significantly from its original meaning.

How can you remember the name of the fourth stomach (abomasum, giara, or abomasum) and what is its function?

The fourth stomach is called "wrinkled stomach" based on its appearance, "giara" in the context of grilled meat, and "abomasum" in English.

The term "wrinkled stomach" comes from the fact that the mucous membrane has fine folds.

The term "true stomach" comes from the fact that it has the same function as the normal stomach of animals other than ruminants.

The fourth stomach is a "true stomach" with a glandular mucosa that secretes hydrochloric acid and pepsin, which acid-hydrolyze microbial and dietary proteins to prepare them for absorption in the small intestine (Ash, 1961). In this sense, it is "genuine."

Furthermore, the presence of wrinkles in the fourth stomach also has significance.

The folded folds in the stomach are folded when empty and unfold when full, increasing the gastric volume (variable volume). The folds also improve the efficiency of stomach wall movement (mixing and stirring), increasing the contact surface between acid and contents, thus facilitating digestion. These are not unique features and are consistent with the general function of the "rugae" of the stomach, including in humans.

Furthermore, the folding of the mucous membrane increases the surface area that accommodates the gastric glands, which secrete gastric juices such as hydrochloric acid and pepsin, allowing for more efficient secretion of acids, enzymes, and mucus.

Therefore, it's easier to remember that the fourth stomach is a "true stomach" with the same chemical digestion function for proteins as other mammals, and that it has gastric glands in its wrinkled folds that serve to temporarily store food.

Abomasum originates from the New Latin abomāsum < ab- "away from" + omāsum "bull's stomach." Therefore, it means "stomach away from the omason (third stomach)" (Wiktionary contributors, 2026).

As for the name "giara," a theory circulating on the internet suggests that it originated from "gibara," meaning "false stomach," because it functions like an intestine despite being the stomach.

However, it is the third stomach that functions like an intestine, while the fourth stomach is the stomach itself, as mentioned above, so this origin theory is not very convincing. It would be more understandable if it was confused with the third stomach, but there is no evidence to support that.

Another theory suggests that the name originated from "gyara" (gyaru) → "giara" (giara) because it was a payment (guarantee) received by people working at U.S. military bases (Tanabe, 2016), but the historical background is unclear, and this theory is also questionable.

References

Ash, RW 1961. Acid secretion by the abomasum and its relation to the flow of food material in the sheep. The Journal of Physiology 156(1): 93-111. https://doi.org/10.1113/jphysiol.1961.sp006660

Bao, W., Lei, C., & Wen, W. 2019. Genomic insights into ruminant evolution: from past to future prospects. Zoological Research 40(6): 476-487. https://doi.org/10.24272/j.issn.2095-8137.2019.061

Clauss, M., Schwarm, A., Ortmann, S., Alber, D., Flach, EJ, Kühne, R., … & Hofer, H. 2004. Intake, ingesta retention, particle size distribution and digestibility in the hippopotamidae. Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology 139(4): 449-459. https://doi.org/10.1016/j.cbpb.2004.10.002

Fowler, ME 2008. Camelids are not ruminants. In: ME Fowler, & RE Miller (Eds.), Zoo and Wild Animal Medicine (6th ed., pp. 375-385). Saunders. ISBN: 9781416057598, https://doi.org/10.1016/B978-141604047-7.50049-X

Grajal, A. 1995. Structure and function of the digestive tract of the hoatzin (Opisthocomus hoazin): a folivorous bird with foregut fermentation. The Auk 112(1): 20-28. https://doi.org/10.2307/4088763

Hailemariam, S., Zhao, S., He, Y., & Wang, J. 2021. Urea transport and hydrolysis in the rumen: a review. Animal Nutrition 7(4): 989-996. https://doi.org/10.1016/j.aninu.2021.07.002

Hofmann, RR 1989. Evolutionary steps of ecophysiological adaptation and diversification of ruminants: a comparative view of their digestive system. Oecologia 78(4): 443-457. https://doi.org/10.1007/BF00378733

Loh, ZH, Ouwerkerk, D., Klieve, AV, Hungerford, NL, & Fletcher, MT 2020. Toxin degradation by rumen microorganisms: a review. Toxins 12(10): 664. https://doi.org/10.3390/toxins12100664

Mackie, RI 2002. Mutualistic fermentative digestion in the gastrointestinal tract: diversity and evolution. Integrative and Comparative Biology 42(2): 319-326. https://doi.org/10.1093/icb/42.2.319

Matsuda, I., Murai, T., Clauss, M., Yamada, T., Tuuga, A., Bernard, H., & Higashi, S. 2011. Regurgitation and remastication in the foregut-fermenting proboscis monkey (Nasalis larvatus). Biology Letters 7(5): 786-789. https://doi.org/10.1098/rsbl.2011.0197

Perez, HG, Stevenson, CK, Lourenco, JM, & Callaway, TR 2024. Understanding rumen microbiology: an overview. Encyclopedia 4(1): 148-157. https://doi.org/10.3390/encyclopedia4010013

Pérez, W., Duro, S., & Gündemir, O. 2023. Anatomical Differences in the Omasum of Weaning Calves Fed with Different Diets. Anatomia 2(2): 176-188. https://doi.org/10.3390/anatomia2020016

Pokhrel, B., & Jiang, H. 2024. Postnatal growth and development of the rumen: integrating physiological and molecular insights. Biology 13(4): 269. https://doi.org/10.3390/biology13040269

Song, Y., Lan,

Tanabe, Shintaro. 2016. On Beef. Poplar Publishing, Tokyo. 169pp. ISBN: 9784591152461

Vendl, C., Munn, A., Leggett, K., & Clauss, M. 2017. Merycism in western gray (Macropus fuliginosus) and red kangaroos (Macropus rufus). Mammalian Biology 86: 21-26. https://doi.org/10.2307/4088763

Wiktionary contributors. 2026, January 22. Wiktionary. https://en.wiktionary.org/wiki/Wiktionary:Main_Page

Zhang, Z., Wang, Y., Si, X., Cao, Z., Li, S., & Yang, H. 2020. Rumen methanogenesis, rumen fermentation, and microbial community response to nitroethane, 2-nitroethanol, and 2-nitro-1-propanol: an in vitro study. Animals 10(3): 479. https://doi.org/10.3390/ani10030479

In short, Adlerian psychology can be described as "a psychology that fosters the ability to live in cooperation with others (community feeling) by choosing one's own life (self-determination), acting in accordance with one's purpose (teleology), and letting go of unnecessary control over others (separation of tasks)."

However, his psychology is buried among many self-help books, and many people may find it somewhat dubious. In fact, even in later generations, his ideas tend to be forgotten and are not quoted even when he says the same things.

Indeed, Adler's ideas are based more on a synthesization of his own clinical experience than on a series of scientific verifications. Furthermore, they address not only facts but also themes beyond the realm of science, such as "how should one live?", and thus have aspects that are closer to philosophy. In that sense, some argue that it is not science.

This article will examine the extent to which Adlerian fundamental factual concepts are accepted in evolutionary biology, psychology, behavioral economics, neuroscience, and brain science. It is based on Miller & Dillman (2016), with additional papers added. Citations of papers mentioned in Miller & Dillman (2016) will be omitted.

In conclusion, the general direction is the same, but there are some differences in our views on conflict and free will.

About Adler and Adlerian psychology

Alfred Adler was a psychologist born in 1870 and died in 1937. The mainstream of psychology during his time was based on the idea that "human behavior is determined by past causes (such as childhood experiences, traumas, and physiological factors)."

For example, Freud emphasized "unconscious desires" and "sexual impulses" as causes. Psychiatry, too, followed a style of "recording symptoms and classifying cause and effect," essentially relying on "accumulating facts." As Adler interacted with patients as a physician, he began to have serious doubts about this "causal explanationism." This is what is called "causal theory."

Adler began to question this. In his youth, he started as an ophthalmologist and internist, treating many patients with lung diseases and tuberculosis. One day, he noticed that even with the same disease, the degree of recovery varied greatly from patient to patient. "Why is it that only those with a 'will to live' recover, even though they have the same disease?" The realization that this could not be explained by mere "physical differences" became Adler's first turning point. In other words, the idea began to take root in him that "people are not passive beings, but rather choose their own way of life." This is what is called "teleology."

After becoming a psychiatrist, Adler developed this idea, applying it to emotions and behavior as well. He parted ways with Freud and founded what is now known as Adlerian psychology, or "individual psychology."

Adlerian psychology is remarkably progressive in that it emphasizes one's own life and individuality, while advocating for exploring connections with society by utilizing one's abilities. I believe it is a very important field of psychology and philosophy, alongside the early Buddhism of Gautama Siddhartha (Buddha/Shakyamuni) in northern India in the 6th century BC, and the Stoic philosophy that began with Zeno in ancient Greece in the early 3rd century BC and spread throughout ancient Greece and Rome, as it helps to let go of the Western notion of pursuing only individual happiness and the extreme Japanese notion of "the nail that sticks out gets hammered down."

Is there any scientific basis for the concept of "community feeling"?

One of the core beliefs in Adlerian psychology is the idea that individuals have an innate capacity for social concern.

In Adlerian psychology, this is called "social interest," and it represents the feeling of being a part of society—whether family, community, or workplace—and the desire to connect with others and contribute. This can range from a family-centered perspective to a global one.

In short, Adlerian psychology argues that this lack of a sense of community—that is, the lack of the feeling that "I am contributing to communities on various scales"—is largely related to feelings of anxiety, unhappiness, isolation, inferiority complexes, and self-centered behavior.

Has research in neuroscience also shown that a sense of community is important?

This view aligns with many neurobiological perspectives on happiness, as stated in the textbook "A Counselor's Introduction to Neuroscience" (McHenry et al., 2014), and several studies suggest that expressing compassion and kindness may enhance relationships and mental and physical health (Fredrickson et al., 2013; Poulin & Holman, 2013).

Oxytocin is a hormone synthesized in the hypothalamus and secreted from the posterior pituitary gland. It is also known as the "love hormone" and is released when we feel social connection or when we care for someone.

Oxytocin is thought to be the source of feelings of happiness that come from having a sense of community, but it has also been found that the secretion of oxytocin does more than that; it also repairs physiological damage induced by stress.

A study by Poulin & Holman (2013) found that people who engaged in prosocial behavior had higher levels of endogenous oxytocin and fewer negative symptoms of stress. The authors suggest that prosocial behavior may be a way for people to stimulate the release of oxytocin and mitigate the negative effects of stress, demonstrating that oxytocin mitigates the adverse health effects of stress.

Another study by Fredrickson et al. (2013) reported that individuals who reported having a higher purpose, being connected to their community, and serving others had lower levels of inflammatory markers, while those who reported more hedonic experiences had elevated levels of pro-inflammatory genes and decreased levels of antiviral response.

Aristotle distinguished between "hedonia," which is happiness that pursues short-term pleasures such as enjoyment, satisfaction, and positive emotions, and "eudaimonia," which is happiness that comes from finding meaning and purpose in life and achieving long-term rather than short-term fulfillment. Here, however, it is interpreted that those who found eudaimonia in a social context were healthier.

These findings suggest, from a physiological and neurological perspective, that having a strong sense of community and contributing to the happiness of others has significant benefits for one's own mental stability and physical health.

Adler also referred to Darwin's theory of evolution, arguing that while other animals evolved physical strength, humans adapted to their environment by forming social groups, and that this is connected to the importance of having a sense of community (Adler & Iwai, 2024).

This idea is also proposed in the form of the social brain hypothesis from the perspective of current evolutionary biology, and can be said to be largely correct (Pedersen et al., 2014; Dunbar, 2024).

Is there any scientific basis for "Adlerian interpersonal relationships"?

Adlerian interpersonal relationships emphasize the separation of tasks (clearly defining one's own responsibilities and those of others, focusing on one's own tasks, and refraining from interfering with others' tasks until requested), rejecting "vertical relationships" (hierarchical relationships) and emphasizing "horizontal relationships" (equal relationships). Encouragement (giving people facing difficulties the energy to overcome them and the confidence that they can do it) is also recommended.

This is somewhat similar to "assertiveness" (self-assertion that respects oneself and others), which originated in behavioral therapy in modern times.

Assertiveness is a communication method and attitude that respects oneself and others, and expresses one's opinions, requests, and feelings frankly, honestly, and on an equal footing. It is consistent with Adlerian interpersonal relationships in that it recommends direct language (a rejection of the "culture of unspoken understanding") and emphasizes equality.

While Adlerian interpersonal relationships themselves lack sufficient scientific validation, several studies have shown that assertiveness can reduce anxiety, stress, and depression (Cantero-Sánchez, 2021; ElBarazi et al., 2024).

Similar ideas are prominent in early Buddhism, Stoic philosophy, and early Christianity, emphasizing the importance of protecting oneself while also showing compassion and respect for others within the community (Bazzano, 2005; Goerger, 2017; Case, 2024).

Is there scientific evidence for the "uniqueness of early childhood experiences"?

Adlerian psychology considers early childhood experiences to be extremely important for the overall development of an individual's view of themselves, others, and the world (Adler, 1956).

Adler (1956) argued that while individuals are born with certain tendencies, the manifestation of specific traits and talents is caused by the community (the surrounding environment).

In other words, this can be rephrased as the idea that "childhood experiences are qualitatively more important than adult experiences and are deeply involved in establishing one's 'lifestyle'."

In Adlerian psychology, "lifestyle" refers to an individual's unique "unconscious blueprint" for living their life, which is a fusion of childhood experiences and the need for belonging. It consists of three elements: self-concept (I am...), worldview (the world is...), and self-ideal (I want to be...).

Therefore, counselors in the Adlerian psychology school try to understand a person's inner world by deeply examining their family structure, including cultural and familial values, expectations of gender roles, the nature of relationships within their birth family, and their psychological birth order.

What about from a neuroscience perspective?

Current brain development models suggest that early childhood experiences have a significant impact on an individual's awareness of themselves, others, and the world, and are thought to complement Adler's view on early childhood experiences (Andersen et al., 2008; McHenry et al., 2014; Perry, 2009; Siegel, 2012).

Brain development begins in the brainstem in the womb and progresses to the prefrontal cortex in early adulthood. Neurologists believe that the fundamental structures related to the brain's regulatory circuits, a key element in discussions of mental health, are primarily formed during the first five years of life (Andersen et al., 2008; Perry, 2009).

In this process, children often internalize the neural circuits of their closest caregivers during their early childhood. While individuals are born with certain genetic predispositions, environmental experiences significantly influence which genetic predispositions are expressed or suppressed through a process called "epigenetics" (Garrett, 2011; Siegel, 2012).

Epigenetics is a mechanism that controls gene function (expression) without changing the DNA base sequence itself. Beginners in biology or those who still hold onto outdated biological ideas tend to think that "behavior is rigidly determined by genes, although there are environmental constraints." However, current biology has proven that, through the action of epigenetics, "individuals have the potential to be either way, and specific genes can be expressed depending on the environment, leading to certain behaviors."

In other words, not only are directly inherited genes involved, but also the environment during childhood, which can influence genetic expression and have both positive and negative effects later in life.

For example, Fallon (2013) examined individuals who engaged in violent psychopathological behavior using brain scans. They found that the participants shared similar neural activity profiles and patterns, specifically "decreased brain function in certain parts of the frontal and temporal lobes, areas generally associated with self-control and empathy."

Up to this point, it could be said that the person has lost their sense of community due to a brain abnormality. In a sense, this is normal.

However, further investigation suggests that some individuals, due to poor upbringing environments, may exhibit neurological activity profiles similar to those of individuals with psychopathic tendencies, even without showing high levels of aggression or low levels of empathy.

In other words, as Adler hypothesized, this suggests the possibility that early childhood experiences influence genetic predispositions.

This is very close to the reality when you consider cases where children born in slums commit crimes or join gangs without realizing it, influenced by their parents and those around them, or cases where children of toxic parents become toxic parents themselves.

Furthermore, Adler's ideas closely align with another psychological concept, "attachment theory," to the point that it's almost a rephrasing of it.

Attachment theory, proposed by psychologist John Bowlby in his research from the 1960s to the 1970s, is a theory that states that the emotional bonds (attachment) that people form with others have a significant impact on their mental health and interpersonal relationships.

Attachment theory was groundbreaking in that it demonstrated that the mother-child relationship, as explained by Freud, is not established through the child learning that "she is the one who breastfed me (satisfaction of need)," but rather through an instinctive and innate mechanism by which the child seeks out their parent, similar to other monkeys.

However, this theory was completed not by directly referencing Adler's earlier work, but by drawing on clinical observations, comparative studies, and references to animal behavior.

Although this attachment theory is old, it is still widely accepted today, and many neuroscientists have shown that attachment is internalized as tacit memory, and that secure attachment is associated with neural structures that promote emotion regulation, fear regulation, harmony, insight, self-understanding, empathy, and morality (Schore & Schore, 2008; Siegel, 2012), while insecure attachment is associated with decreased emotional and social intelligence, executive function, and stress regulation (Perry, 2009).

As described above, Adler's ideas, which emphasized childhood experiences, are still supported today, albeit with some changes in terminology.

Are "teleology" and "the lies of life" correct?

Teleology, in contrast to causalism which states that "human behavior is determined by past causes (such as childhood experiences, trauma, or physiological factors)," is the idea that "people choose their actions and emotions in the present in order to achieve some purpose, and the past causes cited are merely conveniently brought into play to suit that purpose."

This is a point that is often misunderstood because it is only written to this extent in textbooks, but even so, Adler did not deny that genes and the past are the cause of the current situation (Adler and Iwai, 2024).

However, I'm saying that the choice of the cause is ultimately up to the individual.

We often hear people say, "I can't get married because I don't have money and I'm not good-looking," but considering the counterexample of many people around the world who are married despite not having money or good looks, it's clear that even if there is a tendency for this to be the sole cause, it's wrong to attribute it to that. Nevertheless, this kind of expression is often seen.

While abuse can be a cause of delinquency, some people who experience it go on to achieve great success without resorting to crime.

Adler argues that we can choose whether to move in a constructive or unconstructive direction. Adler called the act of not taking action by making plausible excuses a "life lie."

I believe the validity of teleology and the concept of lies in life, that is, the error of causal theory itself, can be easily proven by simply providing exceptions.

So why does the brain make excuses and tell "lies about life" when it should actually be taking action?

In modern terms, this can be seen as "self-deception" (a psychological process in which one deceives oneself to justify or ignore one's own conscience or the truth, even though one knows it) in order to resolve "cognitive dissonance" (psychological discomfort arising from the simultaneous existence of contradictory thoughts or actions in one's mind) in response to "procrastination" behavior caused by "anxiety."

While humans can certainly achieve happiness and survival by maintaining the status quo and avoiding harm or potential threats, maintaining the status quo can also lead to negative consequences (Yamamori et al., 2023).

For example, when going through a job interview, you need to weigh the benefit of getting a new job against the risk of failing or experiencing embarrassment during the interview. While turning down one interview may have little impact on your life, habitually avoiding all job interviews will clearly lead to problems in the long run.

Consistently avoiding long-term benefits for the sake of short-term risks is called "procrastination" in psychology and "present bias" in behavioral economics. As the total of the lost rewards that could have been obtained through diligent effort accumulates, it has an increasingly negative impact, ultimately leading to missing out on important things in life.

Evolutionary biology and behavioral economics have pointed out that this is because humans tend to underestimate future benefits of survival, which are uncertain in the course of evolution (time discounting), and overestimate the risks they may face in the present (Rogers, 1994; Tomono, 2006).

Furthermore, neuroscientifically speaking, mouse experiments have shown that this anxiety process involves excessive strengthening of the connections between the hippocampus/amygdala and the prefrontal cortex (excessive theta wave synchronization), leading to overactivity of interneurons such as VIP ⁺ neurons, PV ⁺ neurons, and SST ⁺ neurons (Mack et al, 2023).

In other words, evolutionarily, the control system of the prefrontal cortex is overly active, making one more susceptible to anxiety. This leads to overestimating current failures and risks (punishments) over future rewards (things one wants to do), causing procrastination. However, because one also understands the downsides, cognitive dissonance occurs, and to resolve this, one resorts to self-deception by telling "lies about life."

In ancient times, when uncertainty was high and death was imminent, this could be considered a highly adaptive evolutionary trait, as it encouraged cautious behavior and promoted the maintenance of the status quo. However, in modern times, where technology has advanced and the risks of action have decreased, it can no longer be considered adaptive (Rogers, 1994; Rasmussen & Dover, 2006; Villmoare et al., 2024).

Early Buddhism and Stoic philosophy also warn against overestimating risks due to "delusions" and "attachments" (Ding et al., 2023). The same is true for early Christianity.

Is there a right way to have courage?

Adler states that "courage" is necessary to overcome "life's lies."

In Adlerian psychology, "courage" refers to the very "vitality" and "motivation" to overcome difficulties and challenges and to take positive action when faced with them.

Adler didn't actually list methods for summoning courage, but based on his intent, the following methods can be considered:

1. Start with small actions
2. Reducing unnecessary anxiety by separating issues
3. Using feelings of inferiority as motivation for growth
4. Be mindful of contributing to others
5. Strengthening self-determination

Of these, the idea of "starting with small actions" is now called "Small Wins" and was rediscovered by Weick (1984).

Small wins are small, achievable successes accumulated day by day towards achieving a larger goal. Weick argues that by breaking down large, complex problems into "small, attainable parts" and accumulating small wins, momentum and support can be gained, making change more likely.

For example, if you're studying, it could be something like memorizing vocabulary for just 10 minutes a day.

This leads to a sense of self-efficacy through achievement, creating a positive cycle of hope, belief, optimism, and confidence, as well as providing feedback for better strategies through learning through practice (Termeer & Dewulf, 2019).

The importance of "just trying something, even if it's small, rather than thinking about a big plan" is still strongly supported today. Agile development, a software development methodology, is one example of this.

On the other hand, there is insufficient research to determine whether separating issues truly leads to anxiety reduction, but it intuitively seems correct.

The idea of separating tasks is almost identical to the concept expressed in Stoic philosophy (Delaney, 2023).

Are there any flaws in Adlerian psychology?

I think there are two main differences between Adlerian psychology and modern thinking.

Is it true that there is no conflict?

First, let's consider the concept of conflict. Adlerian psychology does not recognize conflict between consciousness and the unconscious. This is called holism.

This rejects the idea of "fighting against one's inner self," instead positing that internal conflict exists to achieve one's goals.

This interpretation is not very common in modern times; for example, in evolutionary psychology, the mind is often explained not as a unified entity but as being composed of separate parts (modules) divided according to their purpose. This is also recently referred to as domain specificity (Oda & Otsubo, 2023).

Another example is the "elephant and mahout" metaphor, proposed by Jonathan Haidt, a social psychologist famous for positive psychology (Haidt, 2006). The "elephant and mahout" metaphor is also used in the early Buddhist scripture , the Dhammapada.

"Elephant" refers to the part of the mind that is separate from consciousness and is involved in reactions to stimuli and the formation of motivations through pleasure and displeasure, while "elephant handler" refers to the part that deals with consciousness, language, and rational long-term judgment.

The idea is that the elephant's behavior is a result of the evolutionarily more primitive development of the medulla oblongata, cerebellum, midbrain, and diencephalon, and that these are the main players, while the elephant handler, represented by the cerebral cortex, plays a supporting role, only able to slightly control the direction. In reality, conflicts between different parts of the cerebral cortex are also possible.

However, this is a matter of interpretation. There is no doubt that the elephant and the mahout work together towards some direction (purpose), and I believe that taking a holistic view of life is beneficial in that it prevents unconstructive thinking such as "I suffered again today because of the elephant," and even if the mahout's role is small, it allows us to positively receive messages from different parts of the brain.

Does free will exist?

Next, Adlerian psychology is based on the premise that free will exists. Therefore, it believes that individuals can choose better, more constructive actions for themselves.

On the other hand, in modern times, the prevailing view is the absence of free will (determinism), which holds that all human psychology and behavior are determined by a combination of environmental and genetic factors.

While it might be possible to have a deep philosophical discussion about this, it seems that Adler wasn't interested in such philosophical debates, but rather in assuming the existence of free will and encouraging efforts to change the future.

In psychology, several studies have shown that experimentally giving participants anti-free will messages leads to increased cheating, increased aggression, decreased willingness to help, decreased readiness for exercise, and decreased self-control. While recent meta-analyses have suggested that this has a low impact (Genschow et al., 2023), it may be possible in limited situations.

Fundamentally, accurate prediction of the future is impossible because its initial conditions are unknown, and since it is undetermined, the fact that the future can be changed through learning remains unchanged even if free will does not exist.

Finally, it's important to note that Adler's arguments are about 100 years old, and therefore lack a comprehensive model of early childhood development, meaning they cannot fully explain all aspects of life by modern standards (Miller & Dillman, 2016).

References

Alfred Adler, translated by Toshinori Iwai. 2024. Adler's Words in a Superb Translation: Essential Edition. Discover Twenty-One, Tokyo. 229pp. ISBN: 9784799330104

Bazzano, M. 2005. To feel with the heart of another: Notes on Adler and Zen Buddhism. In P. Prina, A. Miller, C. Shelley, & K. John (Eds.), UK Adlerian Year Book 2005 (pp.42-54). The Adlerian Society UK Institute for Individual Psychology. https://manubazzano.com/wp-content/uploads/2020/11/adler-and-buddhism.pdf

Cantero-Sánchez, FJ, León-Rubio, JM, Vázquez-Morejón, R., & León-Pérez, JM 2021. Evaluation of an assertiveness training based on the social learning theory for occupational health, safety and environment occupational. Sustainability 13(20): 11504. https://doi.org/10.3390/su132011504

Case, B. 2024. Love's Limits in Paul of Tarsus and Seneca the Younger. Religions 15(10): 1169. https://doi.org/10.3390/rel15101169

Delaney, B. 2023. Reasons not to worry: how to be Stoic in chaotic times. Harper, 304pp. ISBN: 9780063314825 [=2024. Philosophy for living peacefully: A way of thinking for living in stressful times, learned from Stoicism. Discover Twenty-One, Tokyo. 421pp. ISBN: 9784799330784]

Ding, X., Ma, Y., Yu, F., & Abadal, LM 2023. The therapy of desire in times of crisis: lessons learned from Buddhism and Stoicism. Religions 14(2): 237. https://doi.org/10.3390/rel14020237

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ElBarazi, AS, Mohamed, F., Mabrok, M., Adel, A., Abouelkheir, A., Ayman, R., … & Mohamed, F. 2024. Efficiency of assertiveness training on the stress, anxiety, and depression levels of college students (Randomized control trial). Journal of Education and Health Promotion 13(1): 203. https://doi.org/10.4103/jehp.jehp_264_23

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When you take up listening to music, singing, or dancing as hobbies, you naturally become interested in rhythm and time signatures.

However, if we consider its origins, there are many aspects that we cannot answer. We often find ourselves moving to rhythms so naturally that we don't even question it, but this ability is actually very limited among living organisms, and it's fair to say that the ability to predict rhythm is unique to humans.

While there's no definitive answer as to the root cause of why that rhythm feels pleasant, one theory suggests that "walking" is deeply involved, and that it's also the origin of 2/4 and 4/4 time signatures. However, the concept of time signatures based on proper music theory itself only emerged in late medieval Europe with the birth of Baroque music.

The triple meter is considered unique and became widely used in 16th-century Austrian waltzes, supposedly because it matched movements that involved rotation.

This article will explain the origins of rhythm and time signatures (2/4, 4/4, and 3/4) from an evolutionary biological and historical perspective.

What is the origin of our sense of rhythm? Humans aren't the only ones who keep the beat!?

Rhythm is defined as "a phenomenon that repeats in a certain pattern that living beings can perceive."

The act of keeping rhythm is a phenomenon that is widely observed in organisms ranging from insects to monkeys, and there are examples such as the following (Iversen, 2016).

It's still unclear whether this sense of rhythm, from insects to humans, is due to genes that were common to all of them in evolutionary biology, but it seems that a certain degree of rhythmic sense is inherited.

What is the origin of the innate human sense of rhythm and the 2/4 time signature? Was the birth of walking the most important factor?

However, humans (and some birds) are thought to have developed a special sense of rhythm called "Rich BPS (Rich Beat Perception and Synchronization)" (Iversen, 2016).

Rich BPS consists of the following elements:

In short, it could be described as the ability to actively and predictively understand rhythm. It is currently believed that animals other than humans either lack this ability or possess it to a very limited extent.

So, what is considered to be the origin of Rich BPS and the 2/4 time signature?

Although there are various theories, walking is considered a very important factor (Iversen, 2016; Fitch, 2016).

For bipedal animals, the most energy-efficient form of walking is thought to be isochronic walking (walking with a constant period). Therefore, they move their left and right legs in a rhythmic manner.

It is believed that all humans, to varying degrees, instinctively acquire a sense of rhythm in order to grasp this sense of tempo.

There is a theory that the feeling of "pleasant rhythm" is an evolutionary by-product of "the motivation for infants to start walking."

Even adults sometimes feel a sense of comfort while taking a walk, which can be rephrased as finding the periodic vestibular and auditory inputs pleasant.

This theory suggests that the enjoyment of walking, stemming from periodic vestibular and auditory input, led to a preference for singing and dancing, which involve movements that stimulate the auditory and vestibular senses.

From another perspective, when bipedal animals walk in groups, if they can synchronize their walking rhythms, they may be able to quickly detect enemy groups, predators, or prey whose footsteps are not in sync. Furthermore, the size of the group can be concealed by layering sounds. This can also be considered a significant advantage of the evolution of Rich BPS.

In music theory, 2/4 time is monotonous because it consists only of strong and weak beats, and nowadays it is only used in marches, popular songs, and a few other genres, having largely given way to 4/4 time.

What is the origin of the 4/4 time signature?

4/4 time is a time signature with four beats per measure. It is similar to 2/4 time, but is generally distinguished by the fact that the strength of the beats progresses from strong to weak to medium-strong to weak. However, since the strength of the beats is not the sole definition of 4/4 time, it seems that the distinction is largely based on convention.

4/4 time, where a quarter note constitutes one beat, is the most widely used time signature in modern music and is used extensively in all genres, including rock, pop, dance music, classical, and jazz.

So, what do you think is the original origin of 4/4 time?

This is indeed considered to be walking (Fitch, 2016). However, the interpretation of walking changes slightly in this case.

When you're walking, you think of it as "sound of kicking with the right foot → sound of lifting the right foot → sound of kicking with the left foot → sound of lifting the left foot."

If we think about it this way, we get a time signature that follows the pattern of "strong beat → weak beat → strong beat → weak beat".

However, to the best of the author's knowledge, there are no papers that offer a clear explanation for the emergence of "mid-strong beats." While it's intuitively clear that the presence of "mid-strong beats" adds complexity and makes the music more enjoyable, it may remain a scientific mystery.

The "4/4 time signature" of "strong beat → weak beat → medium-strong beat → weak beat," based on modern music theory, is believed to have originated in the dance music of the early 17th century Baroque period, but its formation process is not well understood.

Even now, with the advent of DTM (Desktop Music) and the ability to reproduce any kind of music, the fact that even time signatures, along with the aforementioned 2/4 time signature, are still among the most widely used in pop music suggests that we instinctively prefer even time signatures, which resemble walking rhythms.

However, this approach alone cannot explain complex music that is not mainstream, such as music with irregular time signatures, groove, laid-back, push, offbeat, syncopation, and swing. While not mainstream, this music cannot be ignored and has achieved commercial success. While there's a strong sense that "being offbeat is more fun and comfortable," its biological origins remain a great mystery.

However, I also feel that these techniques are valuable when used in a partial manner.

What is the origin of the triple meter?

Triple time is a time signature with three beats per measure, consisting of a strong beat, a weak beat, and another weak beat. It is a time signature commonly used in Western dance music such as waltzes and minuets.

Typical time signatures include 3/4 time, where one beat is a quarter note, and 3/8 time, where two beats are eighth notes.

How did the triple meter come about?

While it may have originated even earlier, in Europe, mensural notation, which emerged in the late Middle Ages and early Renaissance, made it possible to accurately write the length of notes. It was then that, theoretically, triple time became possible.

In fact, the widespread use of triple time is believed to have originated in the waltz, at least in Europe (Fitch, 2016). There are various theories, but it is thought to have become popular in Europe around 1580 and developed from German and Austrian folk dances (Buurman, 2021). As a side note, the Japanese Wikipedia states that it was established in the 13th century, but there is no source for this, and there is no such statement in the English version.

In the Viennese waltz, a series of steps (step → turn → bring feet together) are interspersed between turns, with each "bringing feet together" action serving as a short break to prepare for the next step with the opposite foot. This creates a cycle of six steps, with both the right and left feet taking steps.

The unique aspect of this movement is that it involves rotation, and it is believed that a 3/4 time signature naturally becomes optimal when this action is involved.

Triple time can be considered a relatively new time signature, having emerged after the development of more relaxed dances.

What are some other theories about the evolution of rhythm?

There are several other theories regarding the evolution of rhythm, which I will introduce for reference (Iversen, 2016; Seki & Tachibana, 2023).

The Vocal Learning Hypothesis posits that a sense of rhythm evolved as a byproduct of the ability to imitate voices. This is supported by the fact that parrots and humans possess both the ability to imitate voices and a rich BPS (Beatman-Fetal Positioning System). However, this contradicts the fact that non-vocal mimicry animals (such as sea lions) also possess a sense of rhythm. This might simply be a pre-adaptation for acquiring neural circuits that convert auditory input into motor output.

The theory of sexual selection, proposed by the renowned evolutionary psychologist George Miller, suggests that musical ability was advantageous in mate selection. However, the fact that both sexes possess musical ability contradicts the typical theory of sexual selection. Nevertheless, since there are differences in musical preferences between men and women, it is possible that sexual selection occurred incidentally after the evolution of rhythmic sense.

The social bonding and group cooperation theory posits that rhythm evolved to promote group bonding and cooperative behavior. This seems natural when we consider the sense of unity we feel and the mosh pit we form at live concerts today. However, natural selection usually occurs among individuals or closely related groups, and this type of evolution falls under the category of "multilevel group selection," which is different from the usual pattern. This idea is not very popular in evolutionary biology because there is debate about its interpretation (although I think there is some truth to it). Moreover, it seems that rhythm is not the only thing that could promote bonding, so perhaps the sense of unity is a consequence of the evolution of rhythm.

The maladaptation theory (music being a byproduct) was proposed by the famous psychologist Steven Pinker, who argued that music is an "auditory cheesecake," a pleasure-seeking technique, and not an evolutionary adaptation. While it's true that modern, pleasant music might be like a cheesecake, the very sense of rhythm itself seems to be an evolutionary product.

Currently, the prevailing view seems to me that the fundamental sense of rhythm evolved in conjunction with walking, but this may change depending on future research.

References

Buurman, E. 2021. Early Viennese Waltz Dances. In: E. Buurman (Ed.), The Viennese Ballroom in the Age of Beethoven (pp. 32-54). Cambridge University Press. ISBN: 9781108797856, https://doi.org/10.1017/9781108863278.003

Fitch, WT 2016. Dance, music, meter and groove: a forgotten partnership. Frontiers in Human Neuroscience 10: 64. https://doi.org/10.3389/fnhum.2016.00064

Iversen, JR 2016. 21 In the beginning was the beat: evolutionary origins of musical rhythm in humans. In: R. Hartenberger (Ed.), The Cambridge Companion to Percussion (pp. 281-295). Cambridge University Press. ISBN: 9781107472433, https://doi.org/10.1017/CBO9781316145074.022

Seki, Yoshimasa & Tachibana, Ryosuke. 2023. Animal rhythm synchronization ability and its origins. Journal of the Acoustical Society of Japan 80(1): 33-40. https://doi.org/10.20697/jasj.80.1_33

In Japan, the Japanese black bear (Ursus thibetanus japonicus) is found on Honshu and Shikoku, while the Hokkaido brown bear (Ursus arctos yesoensis) is found on Hokkaido.

It has been reported that by 2025 these bears were increasing their activity in populated areas, leading to a frequent occurrence of tragic incidents. Such bear attacks have existed since ancient times and are a problem not only in Japan but all over the world.

Among those people, many might wonder, "How are bears related to our lives?"

Some people hold the extreme opinion that "bears should be exterminated!" I think they are free to hold such opinions, but I believe they may lack sufficient knowledge about the benefits that bears provide to the ecosystem.

While I believe that culling bears is sometimes unavoidable when necessary, as someone involved in environmental assessment work, I will deliberately consider the practical benefits (advantages and advantages for humans) rather than focusing on animal welfare.

To put it simply, "Bears enrich forests through seed dispersal and predation, and indirectly benefit humans through the benefits those forests provide."

Reason 1: Because seed dispersal will decrease, leading to a reduction in forests or an increase in simple forests.

Although the Japanese black bear is an omnivore, it is known that 80-90% of its diet consists of plant-based foods (Hashimoto and Takatsuki, 1997).

Among these, it has been found that they eat the fruits of 23 different plants, and fecal analysis has revealed that they also expel the seeds of 16 different plants alive (Koike et al., 2003).

The plants include six varieties of cherry blossoms, such as the mountain cherry (Prunus jamasakura), and are familiar and well-known to Japanese people who love cherry blossom viewing.

In addition, there are studies showing that, beyond just the number of species, the distribution of mountain cherry trees, for example, is being pushed up to higher altitudes geographically by the Japanese black bear (Naoe et al., 2016).

The same is true for brown bears; it has been reported that bears, not birds, disperse the majority of seeds of the American berry shrub , Oplopanax horridus, in southeastern and northern Alaska, United States (Levi et al., 2020).

While there is still insufficient research on the Hokkaido brown bear, it is thought that berries play a similar role in their diet (Sato, 2005; 2018). In one study, after eating three types of berries, including Actinidia arguta, most of the seeds were excreted intact, with 941 TP3T remaining undamaged, and the germination rate was increased (Tsunamoto et al., 2024).

Furthermore, it has been confirmed that brown bears supply food to seed-eating rodents through their feces (Levi et al., 2020). Mice readily carry the seeds contained in the bear's droppings.

In other words, this means that bears are increasing the diversity of plants and animals in the forest.

It is well known that forests provide a variety of "ecosystem services," such as fixing atmospheric carbon dioxide and converting it into biomass, acting as a "green dam" to absorb rainwater and reduce the risk of floods and water shortages, stabilizing the ground to prevent landslides and mudslides, regulating the climate, and providing recreational areas (Nakashizu, 2017; Tanaka and Nagahiro, 2019).

Furthermore, numerous studies have shown that insects that thrive in forests contribute to the pollination of our agricultural products (Ulyshen et al., 2023), and many crops cannot bear fruit without pollination by wild insects. For example, in Japan, it has been found that buckwheat pollination is facilitated by insects originating from forests (Taki et al., 2010).

It is well known that these ecosystem services are more abundant in forests with higher biodiversity (Brockerhoff et al., 2017).

Therefore, it is highly likely that the existence of bears indirectly benefits humans as well.

However, it can be said that the extent to which this affects the overall situation is currently unknown.

Reason 2: Because it will get rid of the bees.

Japanese black bears also readily eat honeybees, wasps, and ants (Hashimoto and Takatsuki, 1997). These make up the largest proportion of their animal-based diet. This is because they are eusocial insects and exist in colonies, making them an important source of protein for Japanese black bears. The same is true for Hokkaido brown bears (Sato, 2005).

Honeybees and wasps, in particular, are relatively aggressive insects and possess venomous stingers, making them a common cause of harm to humans. In the decade from 2002 to 2011, wasp stings averaged 19.4 deaths per person (Kanayama, 2013). The number of injuries is likely much higher.

Japanese black bears may be reducing the populations of honeybees and wasps by preying on them. In particular, wasps are almost the top predator among insects and have only a handful of natural enemies (Noguchi & Ikeda, 2022), and even among vertebrates, the number of proven natural enemies is limited, such as the honey buzzard bird and the marten mammal (Hirakawa & Sayama, 2005).

The Japanese black bear is undoubtedly an important natural enemy of honeybees and wasps, and it likely also brings benefits to humans. However, the quantitative aspects remain unclear.

From the perspective of human benefits, it boils down to the question, "Which is more important, eliminating bears or wasps?", but I've encountered wasps far more often.

Furthermore, as top predators among insects, hornets prey on a wide variety of insects. Hornets, which have invaded Hawaii and New Zealand as an invasive species, are known to have a significant impact on native ecosystems, primarily affecting moth and butterfly larvae (New, 2016).

In Japan, the Japanese black bear may be reducing the population of wasps, thereby lowering predation pressure and increasing the diversity of prey and sub-predators. This would likely lead to the aforementioned increase in ecosystem services.

Reason 3: Salmon spread nutrients from the sea onto land through their predation.

While there are currently no confirmed instances of Japanese black bears eating fish (Hashimoto & Takatsuki, 1997), Hokkaido brown bears have been confirmed to eat salmonid fish such as pink salmon and chum salmon, although the amount has been decreasing due to development (Sato, 2005). The predation pressure is so strong that it alters the breeding morphology of pink salmon (Sahashi et al., 2020), and they serve as an important food source before hibernation. Some studies also suggest that females can produce more offspring as their consumption of salmon increases (Sato, 2018).

At first glance, this might sound like simple predation, but in fact, by consuming such large quantities of salmon, the Hokkaido brown bear is returning nutrients, primarily nitrogen, from the sea to the land (Koshino et al., 2013; Sato, 2018). This might be an overlooked point.

It has been pointed out that this is true not only for the Ezo brown bear in Japan but also for brown bears around the world (Levi et al.,, 2020).

Furthermore, it has been discovered that salmon not only enrich the forest through their feces, but also enrich the rivers themselves, as land animals and aquatic insects utilize the carcasses of the salmon they kill.

Normally, nutrients would be washed away by gravity, but the fact that this doesn't happen is thanks to salmon and brown bears.

However, you might wonder, "Isn't nitrogen already transported inland by seabird droppings, and isn't it okay because leguminous plants and other organisms fix nitrogen from the air back into the soil?"

However, studies investigating nitrogen isotope ratios have confirmed that riparian plants actively utilize nitrogen derived from salmon, increasing physiological activity, productivity, and community structure, and exhibiting specific changes such as an increase in the nitrogen ratio within the plant body and an increase in stomatal density (Levi et al., 2020).

Almost exclusively bears are capable of doing something similar, and even animals that eat salmon only consume the carcasses left behind after bears have hunted or after floods.

Therefore, the Hokkaido brown bear may play a significant role in enriching the rivers and riverside forests of Hokkaido.

Reason 4: Because digging enriches the land.

Brown bears are known to dig up the underground parts of herbaceous plants in subalpine grasslands such as snowfield communities (Sato, 2018). This is also true for the Ezo brown bear in Japan.

Although there is a lack of research in Japan, it has been reported that in Glacier National Park in Montana, USA, this "digging" behavior has led to an increase in bare ground, a rise in ammonia and nitrate concentrations in the soil, and an increase in seed production of the yellow dogtooth violet plant.

In other words, the feeding behavior of brown bears is indeed contributing to an increase in soil fertility. Organisms that modify the landscape through certain behaviors, creating habitats for other organisms, are called "ecosystem engineers." Earthworms and beavers are typical examples, but brown bears have been shown to be part of this group as well.

Reason 5: Because they eat herbivores and return them to the soil.

Japanese black bears are known to feed on Japanese serows and Japanese deer, while Hokkaido brown bears feed on Hokkaido deer (Hashimoto and Takatsuki, 1997; Sato, 2005).

However, instances of them directly eating living animals are rare, except for weakened individuals, and it is generally believed that they feed on carcasses killed through hunting or extermination (Hashimoto & Takatsuki, 1997; Sato, 2018).

While brown bears in other countries sometimes prey on young herbivores, and given the limited opportunities to directly observe Japanese black bears and Hokkaido brown bears, it's possible they are preying on more animals than we know, but this is currently unknown.

If they are preying on herbivorous mammals, they may be regulating their populations.

Even if they are scavengers, they still play a role in returning herbivorous mammals to the soil.

However, this role may be replaceable by many other animals.

Reason 6: They eat mushrooms and then spread their spores.

It has been found that the American black bear (Ursus americanu s) and the grizzly bear (Ursus arctos horribilis), which are distributed in North America, eat fungi (mycorrhizal fungi, which include ascomycetes and basidiomycetes) and excrete some of the spores alive as they pass through their digestive tract (Cázares & Trappe, 1994; Mattson et al., 2002).

This may help distribute less mobile fungi over a wider area, contributing to increased fungal diversity and the diversity of host plants. Furthermore, free-living nitrogen-fixing bacteria that inhabit the fruiting bodies of mycorrhizal fungi are also dispersed along with fungal spores through mammalian feeding.

Of course, people who enjoy mushroom hunting as a hobby are directly benefiting from it.

While this hasn't been extensively studied in Japan, it's known that Japanese black bears also eat mushrooms (Hashimoto & Takatsuki, 1997), suggesting a similar role. However, squirrels, flying squirrels, mice, and Japanese macaques also eat mushrooms (Sawada, 2014; Sagara, 2021).

In conclusion: Is the role of the bear replaceable?

Up to this point, we have listed the various benefits of bears across different ecosystems, but their actual impact on the ecosystem as a whole remains unknown due to a lack of research.

The Asiatic black bear in Kyushu had already had a limited habitat and a small population by the early Showa period, and was extinct after the last sighting in 1957 (Nishida et al., 2022). However, it is unknown whether this has led to the effects described above.

However, human imagination has its limits, and it would be nearly impossible to consider all the consequences of an irreversible extinction.

As known as the "rivet hypothesis," even if one part of an airplane is missing and it can still fly (even if one species disappears and the ecosystem appears unchanged), as the number of missing parts increases, it can rapidly become impossible to fly (the ecosystem collapses) (Eisenhauer et al., 2023). In recent years, this has been demonstrated under the term "redundancy."

Even bears, in the present, may have their role taken over by other animals, but if other species become extinct, it's uncertain whether that will actually happen.

As depicted in the manga "Golden Kamuy," there is a view that the Japanese should adopt a similar approach to dealing with bears, just as the Ainu once distinguished between "good" brown bears (Kimun Kamuy) that do not attack humans and "bad" brown bears (Wen Kamuy) that do, and treated them accordingly (Matsuda, 2008). Considering that extermination is irrational from a cost, interest, and ethical standpoint, I also believe that this serves as an example to consider the duality of nature and that rational coexistence is needed.

Of course, balancing extermination and protection is very difficult, so please consider the above-mentioned impacts and deepen your discussion.

References

Brockerhoff, EG, Barbaro, L., Castagneyrol, B., Forrester, DI, Gardiner, B., González-Olabarria, JR, … & Jactel, H. 2017. Forest biodiversity, ecosystem functioning and the provision of ecosystem services. Biodiversity and Conservation 26(13): 3005-3035. https://doi.org/10.1007/s10531-017-1453-2

Cázares, E., & Trappe, JM 1994. Spore dispersal of ectomycorrhizal fungi on a glacier forefront by mammal mycophagy. Mycologia 86(4): 507-510. https://doi.org/10.1080/00275514.1994.12026443

Eisenhauer, N., Hines, J., Maestre, FT, & Rillig, MC 2023. Reconsidering functional redundancy in biodiversity research. npj Biodiversity 2(1): 9. https://doi.org/10.1038/s44185-023-00015-5

Kanayama, Akihiro. 2013. Bee species and control methods. Pest Control Tokyo (64): 20-25. https://www.pestcontrol-tokyo.jp/img/pub/064r/064-8.pdf

Koike, S., Hazumi, T., & Furubayashi, K. 2003. Possible seed dispersal of the Japanese black bear (Ursus thibetanus japonicus). Wildlife Conservation 8(1): 19-30. https://doi.org/10.20798/wildlifeconsjp.8.1_19

Koshino, Y., Kudo, H., & Kaeriyama, M. 2013. Stable isotope evidence indicates the incorporation into Japanese catchments of marine-derived nutrients transported by spawning Pacific Salmon. Freshwater Biology 58(9): 1864-1877. https://doi.org/10.1111/fwb.12175

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Sato, Kiwa. 2018. Forests as habitats for brown bears and their management—natural forests, plantations, understory vegetation, and deer. Northern Forest Research 66: 1-3. https://doi.org/10.24494/jfsh.66.0_1

Sawada, Akiko. 2014. Mushroom-eating behavior in primates: Future challenges and possibilities. Primate Research 30(1): 5-21. https://doi.org/10.2354/psj.30.010

Taki, H., Okabe, K., Yamaura, Y., Matsuura, T., Sueyoshi, M., Makino, SI, & Maeto, K. 2010. Effects of landscape metrics on Apis and non-Apis pollinators and seed set in common buckwheat. Basic and Applied Ecology 11(7): 594-602. ISSN: 1439-1791, https://doi.org/10.1016/j.baae.2010.08.004

Tanaka, K. & Nagahiro, S. 2019. A comparison of subjective and inferential evaluations of the value of forest ecosystem services. Environmental Economics and Policy Studies 12(1): 44-58. https://doi.org/10.14927/reeps.12.1_44

Tsunamoto, Y., Tsuruga, H., Kobayashi, K., Sukegawa, T., & Asakura, T. 2024. Seed dispersal function of the brown bear Ursus arctos on Hokkaido Island in northern Japan: gut passage time, dispersal distance, germination, and effects of remaining pulp. Oecologia 204(3): 505-515. https://doi.org/10.1007/s00442-024-05510-5

Ulyshen, M., Urban-Mead, KR, Dorey, JB, & Rivers, JW 2023. Forests are critically important to global pollinator diversity and enhance pollination in adjacent crops. Biological Reviews 98(4): 1118-1141. https://doi.org/10.1111/brv.12947

The term "mena centipede" refers to a group of centipedes belonging to the genus *Centipede* in the family Scolopendridae, order Scolopendromorpha. These centipedes are burrowing and rarely seen by the average person, but their most striking feature is their strangely enlarged final legs. While there have been various theories regarding the function of these final legs, recent research suggests they are likely used as a means of defense against predators. However, there is currently very little research on the ecology of *Centipede* species in Japan. This article will explain the ecology of *Centipede*.

What is a Menashi centipede?

Cryptops are a general term for species belonging to the genus Cryptops in the family Cryptodoridae, order Scolopendromorpha.

In Japan, only three species of Cryptops are known: Cryptops japonicus, Cryptops striatus, and Cryptops nigropictus. The distinctions between these species are described in Aoki (2015).

This group of centipedes is relatively subterranean and rarely wanders above ground, making them quite uncommon and difficult to find. However, those of us who regularly study soil animals, like myself, occasionally come across them.

Although it is not listed in Japan's Ministry of the Environment's Red Data Book, it is treated as an endangered species in some prefectures, such as Chiba and Saitama.

The most distinctive feature of this group of centipedes is that their last pair of legs, or the final pair of legs, are exceptionally large compared to other centipedes and are covered in spines called "serrations."

As its name "eyeless centipede" suggests, one of its distinguishing features is the absence of eyes (compound eyes). However, the absence of compound eyes is also common to the Scolopendromorpha order and the Scolopendridae family, which includes species like the geometrid centipede and the red centipede. These are thought to be adaptations to life underground in the absence of light (Aoki, 2010).

Like many centipedes, the flat-nosed centipedes are carnivorous.

What is the role of the last pair of legs in the flat-legged centipede? Is it for predation or defense?

Every time I saw this legless centipede, I wondered, "Why are its legs shaped like that?"

Centipede research is lagging behind in Japan, and ecological research is even further behind; there is virtually no research on the Japanese species *Centipede japonica*.

However, various studies have been conducted on members of the genus *Centipede* from other countries, so I will share them here (Lewis, 2010; Kenning at al., 2017).

It was initially thought that the last pair of legs of the flat-legged centipede were used for predation.

From its appearance, it seems that this centipede has serrations on the inside of its legs, which suggests it can grip firmly. Closely related species, such as those in the genera * Theatops *, * Plutonium*, and *Centipede*, have strong muscles and pincers, and have been observed actually catching prey.

However, while there is one recorded instance of such observation in the flat-legged centipede, the centipede ultimately failed to capture and kill its prey with its last pair of legs, and other studies only record that the centipede does not use its last pair of legs, but instead grabs its prey with the mandibles on its head and eats it.

Therefore, recent research suggests that the use of the flat-nosed centipede may be different from this.

It's for defense. Specifically, the idea is that when attacked by a predator, the animal reflexively grabs with its last pair of legs, and the serrations on the inside of those legs create frictional resistance, allowing it to stick to the predator's body.

This phenomenon has been directly observed in one instance, in which a species of centipede (Phidippus genus) attacked a species of centipede (Phidippus genus), and the centipede (Phidippus genus) retaliated with its last set of legs, leaving the legs attached to the body of the centipede.

Furthermore, when specimens of the genus *Centipede* are prepared, the last pair of legs tend to detach easily due to the impact, and the detached legs are severely bent. I have actually seen a specimen of *Centipede* from Japan that was missing its last pair of legs. This fact also supports the idea that the legs developed for defensive purposes, as it would be problematic if *Centipede* used them for predation, as the legs not easily detaching would be a problem.

However, determining specifically which types of predators this last-stepped leg is advantageous against remains a subject for future research.

The final stepping leg had other roles too!?

However, the serrations on the inner side of the last step remain a mystery.

In large males of the New Zealand species C. polyodontus and C. lamprethus, the serrations on the teeth are arranged in 2 to 4 rows, while females have only one row of serrations, and these serrations are larger than those of the males.

This fact indicates sexual dimorphism in the serrations on the inner side of the last step, and sexual dimorphism usually arises through the evolutionary process of sexual selection. Therefore, it suggests that the use of these serrations differs between males and females for some reason.

However, the specific differences in their uses are still not well understood. One researcher suggests that they may be used for sex identification in species recognition. Mating behavior in the genus *Centipedes* has not yet been observed, but some other centipede species perform a courtship ritual called "tapping," where they tap or stroke the last legs of the opposite sex with their antennae. If *Centipedes* also do this, it would be a way to gather information about the distribution of their partner's serrations.

While no similar cases have been observed in Japanese centipedes, it's possible that the final set of legs changes in various ways during the evolutionary process, such as for attack, defense, and mating.

References

Aoki, Jun-ichi. 2010. Soil Zoology: Focusing on Classification, Ecology, and Relationship with the Environment. Hokuryukan, Tokyo. 797pp. ISBN: 9784832608375

Aoki, Jun-ichi. 2015. Illustrated Key to the Classification of Soil Animals of Japan (2nd edition). Tokai University Press, Hadano. 1969pp. ISBN: 9784486019459

Lewis, J. 2010. On the function of the ultimate legs of Cryptops and Theatops (Chilopoda, Scolopendromorpha). International Journal of Myriapodology 3(2): 145-151. https://doi.org/10.1163/187525410X12578602960542, https://brill.com/view/journals/ijm/3/2/article-p145.xml

Kenning, M., Müller, CH, & Sombke, A. 2017. The ultimate legs of Chilopoda (Myriapoda): a review on their morphological disparity and functional variability. PeerJ 5: e4023. https://doi.org/10.7717/peerj.4023

When you think of mosquitoes, you probably imagine blood-sucking creatures that are a real nuisance in the summer. However, there is a type of mosquito in Japan that does not suck blood at all. The Towada mosquito is harmless as an adult, does not suck blood, and is the largest and most beautiful mosquito in Japan, which is in itself a distinctive feature. Surprisingly, its larvae live in puddles of water in tree hollows, where they feed on the larvae (wrigglers) of other mosquitoes. This article will explain the ecology of the Towada mosquito.

The Towada wolf mosquito is a harmless and beautiful mosquito.

When you think of mosquitoes, you probably imagine them as blood-sucking creatures that are a real nuisance in the summer. (However, only female mosquitoes suck blood because they need nutrients to lay eggs.)

In tropical regions, they can transmit infectious diseases such as dengue fever, which is another reason why they are disliked by humans.

But did you know that there are mosquitoes in Japanese forests that, despite being related to mosquitoes, do not suck blood at all?

Its name is Toxorhynchites towadensis, and as its name suggests, it is a very large mosquito, measuring 10-13 mm, and is known as the largest mosquito in Japan. Incidentally, "Towada" comes from Lake Towada (Aomori Prefecture to Akita Prefecture), where it was first discovered. In reality, it is known to be widely distributed in Hokkaido, Honshu, Shikoku, Kyushu, Tsushima, and Yakushima (Sasaki et al., 1995).

While most mosquitoes have scales on their body surface, the Towada mosquito has a shimmering bluish-purple coating, making it very beautiful to look at.

I once saw this mosquito in Minoo Park in Osaka Prefecture. It flew around the tree trunks leisurely and with ease, giving off a dignified and elegant impression.

Adult Towada wolf moths appear from May to August, and both males and females are known to feed on nectar and other bodily fluids.

Therefore, it can be said that this type of mosquito is completely harmless to humans.

Although it is not included in the Ministry of the Environment's Red List, it is listed in the Red Data Lists of 14 prefectures and is considered an endangered species.

The Towada wolf was a "mosquito that eats mosquitoes"!?

However, some might wonder what such a large mosquito eats and how it grows. Normally, female mosquitoes feed on blood to obtain protein for egg-laying. So how does such a large mosquito obtain nutrients without feeding on blood?

This aspect remained a mystery for a long time, ever since the discovery of the Towada mosquito in 1916. However, the ecology of this mosquito was finally revealed in 1952 (Ishimura, 1952).

The study revealed that the larvae of the Towada mosquito live in puddles of water inside tree hollows (holes in the base or trunk that are accidentally formed by injuries or obstacles), and that they prey on the larvae (wrigglers) of other blood-sucking mosquito species that are also present in these cavities.

Specifically, mosquitoes such as Aedes niveus, Aedes oreophilus, Aedes flavopictus, and Tripteroides bambusa are believed to inhabit tree hollows.

This essentially means it's a "mosquito that eats mosquitoes." This fact is quite interesting. However, it seems that it sometimes preys on the larvae of midges (a different group of flies that resemble mosquitoes but don't suck blood) and water beetles (a type of beetle).

In July and August, newly hatched first-instar larvae of the Towada genus will bite and eat larger larvae (1st to 3rd instar) of the Aedes genus, surfacing to devour them. They typically do not actively pursue prey, but quickly capture approaching larvae by moving only their cephalothorax. They then begin eating from the bitten area, leaving only the head and part of the thorax remaining.

It is thought that the reason why adult Towada wolf larvae can maintain their large size is because they are actually high-level predators.

Another interesting finding is that when other mosquito larvae are found in high densities, they begin to kill their prey without consuming any of it (Yasuda, 1995).

The reason for this strange behavior is not well understood, but it turns out that other Towada wolves in the same area are quite formidable rivals, and cannibalism has occurred.

Therefore, it's possible they're launching preemptive attacks without determining whether the target is prey or a rival, or that they're eliminating their rivals' food sources, but these are still just hypotheses.

Is the Towada wolf useful?

This type of behavior may be regulating the population of the Aedes mosquito species. The tree hollows act like traps, and if Aedes mosquitoes lay their eggs there, it could lead to their complete extinction. While some aspects of their role in the natural world remain unclear, it's undeniable that the Towada mosquito, as well as the tree hollows and the trees themselves, play some kind of role.

More recently, members of the genus Aedes, including Aedes towada, are attracting attention as biological control agents (biopesticides) (Sukupayo et al., 2024). This is because they can kill Aedes mosquitoes in an environmentally friendly way without using chemicals like insecticides. This may reduce the number of infectious diseases they transmit.

As mentioned above, when other mosquito larvae are present in high densities, they will kill the prey without consuming any of it, so it's possible that there are effects beyond simply using them as food.

While it's still unclear whether this will be put into practical use, please do pay attention to these kinds of mosquitoes when you walk through the forest!

References

Sasaki, Hitoshi; Kusui, Yoshihisa; Nishijima, Hiroshi; Hasegawa, Tsutomu; and Kanasugi, Takao. 1995. Collection records of *Towada's wolf* in Hokkaido. *Sanitary Zoology* 46(1): 75-76. https://doi.org/10.7601/mez.46.75

Sukupayo, PR, Poudel, RC, & Ghimire, TR 2024. Nature's Solution to Aedes Vectors: Toxorhynchites as a Biocontrol Agent. Journal of Tropical Medicine 2024(1): 3529261. https://doi.org/10.1155/2024/3529261

Yasuda, H. 1995. Effect of prey density on behavior and development of the predatory mosquito, Toxorhynchites towadensis. Entomologia Experimentalis et Applica 76(1): 97-103. https://doi.org/10.1111/j.1570-7458.1995.tb01949.x

Ishimura, Kiyoshi. 1952. On the larval stage of the Towada wolf. Sanitary Zoology 3(1-2): 12-19. https://doi.org/10.7601/mez.3.12

When you hear the word "ant," you might picture a black insect crawling on the ground. However, there are actually many unknown species of ants living underground, and among them, the Hooked Ants and Pterodactylus ants have a very unique shape with hook-shaped abdomens. While they certainly look interesting, their function remained unknown for a long time. However, with further research, it has been discovered that Hooked Ants specialize in eating insect eggs, and that the hooks on their abdomen are an adaptation for handling these eggs. In recent years, the types of insect eggs they feed on have also gradually become clearer. This article will explain the morphology and ecology of Hooked Ants and Pterodactylus ants.

Are there ants in Japan with a hook-shaped abdomen?!

What image comes to mind when you hear the word "ant"?

In Japan, the most common types of ants are the brown ant and the black garden ant, both of which are small, black, and can be seen actively moving around even on the ground.

However, it is known that there are many types of ants called "subterranean" ants that cannot be found unless the soil is dug deep into the ground.

It's rare to encounter ants like these, and many people may not even know they exist. However, such species are important for ant research, and when I was a student, I often dug up soil in rural areas of Nara Prefecture to search for ants in order to study the different ant species there. I published the results of that research in a paper (Ikeda, 2020).

By the way, among those kinds of ants, there is one that I find particularly interesting.

That's a type of ant called a hooked ant, a general term for ants belonging to the genus *Hooked Ants* in the family Formicidae.

The most distinctive feature of this species of ant is its hook-shaped abdomen. This is the origin of its name, which means "hook-bellied ant." The hook is fixed, and the ant cannot straighten its abdomen backward.

Furthermore, as a result of adapting to a subterranean lifestyle, their compound eyes have degenerated, and their body color is brown instead of black like that of terrestrial species. This is because they do not need to mitigate the damage from ultraviolet rays caused by sunlight, as humans do with black hair.

This species is interesting just for its appearance, and on top of that, it's quite rare, so finding one is a real surprise.

In Japan, several species of ants named after people are known, including * Proceratium itoi*, * Proceratium watasei*, * Proceratium morisitai*, and * Proceratium japonicum*.

Although they belong to different genera, the ants * Discothyrea sauteri * and * Discothyrea kamiteta* have very similar abdominal shapes (the latter having compound eyes).

The "hooks" on its belly were for carrying insect eggs!

But what role do these "hooks" on its belly play?

The mystery of the "hook" on its belly wasn't immediately solved. This is because it lives underground, making it very difficult to study its ecology.

However, in 1957, a researcher named Brown was the first to report that a species of ant from the genus *Hypnacea*, native to North America, was storing arthropod eggs in its nest.

Mr. Brown also succeeded in raising a species called Proceratium silaceum by feeding it only spider eggs.

In other words, it has become clear that the ant species *Hydrophilus spp.* specializes in feeding on insect eggs. Isn't that surprising?

However, some people may still not understand how the "hook" on the belly is connected to the eggs.

Following this, Japanese researcher Keiichi Masuko partially reported on how ants such as the genus *Cortinarius* and *Cortinarius* handle eggs (Masuko, 1981).

According to the study, the Daruma ant stands on the floor using its middle and hind legs, and uses its two front legs and the straight end of its forelegs to hold the eggs stored in the nest. It has been observed that the ant skillfully rotates the eggs while licking their surface clean with its mouthparts.

Furthermore, in the Japanese spindle ant (Rana japonica), it has been observed that when the ant cuts open the eggs with its mandibles, it not only holds the eggs with its legs but also firmly grips them by pressing the tip of its abdomen against them.

Based on these observations, it's likely that the hooks on its abdomen are used to clean or eat insect eggs.

However, they don't always handle the eggs with their belly; they might use their mandibles to hold the eggs in their mouths when transporting them.

They say they eat "insect eggs," but what kind of insects specifically?

By the way, I've been referring to them as "insect eggs," but what kind of eggs are they specifically?

In fact, this point has remained unclear for a long time.

As mentioned above, Mr. Brown, who was the first to report on egg storage in the ant species *Rhynchosoma rhodopolium*, reported in various books that "the ants feed on spider eggs!" after feeding them spider eggs "in captivity" and observing the colony's growth.

Brown's report was based solely on observations made "in captivity," and failed to verify the identity of the eggs when found in the wild. As a result, the question remains: "Do ants of the species *Hydropsyche* really feed on spider eggs in the wild?"

Therefore, Keiichi Masuko, through extremely meticulous and painstaking work, investigated the identity of the eggs of the ant species *Rhynchosoma rhodopolium* in the wild (Masuko, 2019).

The method was quite simple: they hatched 1,800 eggs from a wild ant nest. However, even though the method is simple, finding the ant nests, which are difficult to locate, and examining so many delicate eggs is no easy task.

The investigation revealed that the 1,800 eggs contained only centipedes such as Lithobius, hemipterans such as Macroscytus japonensi, and harvestmen such as Proscotolemon sauteri.

Furthermore, there were no spider eggs at all. This contradicts Brown's report.

However, it would be premature to conclude from these results that all species of ant species prey exclusively on the eggs of these three groups. The ecology of ant species found in North America may differ from that of ant species found in Japan, and the four species of ant species and two species of ant species found in Japan also differ morphologically, which may also stem from the differences in the eggs they prey on.

In fact, another study has shown that the common ant *Argynnis paphia* feeds exclusively on spider eggs, and in one instance, *Argynnis spp.* collected eggs from a slightly different centipede species called * Esastigmatobius *.

This behavior may also affect other insects and ecosystems. Stone centipedes and harvestmen are carnivorous and are top predators among small animals, and while stink bugs feed on seeds, they emit a foul odor as adults, making them unaffected by most animals. However, it appears that the hooked ant regulates the populations of these insects while they are still in the egg stage.

Furthermore, while the stink bug that was preyed upon in this case left its eggs unattended after laying them, many other species in the family Pentatomidae are known to protect their eggs (subsocial behavior). These ecological differences may also be partly driving the evolution of the ant species *Rhynchosoma rhodopolium*.

While there are still many unknowns about this group, it's possible that their unique diet plays a crucial role in maintaining balance within the entire ecosystem. Though minor, they are definitely worth keeping a close eye on.

References

Ikeda, K., Kasai, H., Goda, A., Murakami, K., Ishihara, T., Nakamura, K., and Sawabatake, T. 2020. Ant fauna around Kinki University Nara Campus. Kinki University Faculty of Agriculture Bulletin 53: 46-70. ISSN: 2189-6267 https://kindai.repo.nii.ac.jp/records/20942

Masuko, Keiichi. 1981. Predatory behavior of forest floor ants: A few examples. Insects and Nature 16(3): 19-25. ISSN: 0023-3218.

Masuko, K. 2019. Predation on non-spider arthropod eggs and colony bionomics of the ant Proceratium itoi (Hymenoptera: Formicidae). Annals of the Entomological Society of America 112(4): 372-378. https://doi.org/10.1093/aesa/saz012

Japanese Ant Database Group. 2003. Complete Illustrated Guide to Japanese Ants. Gakken Co., Ltd., Tokyo. 196pp. ISBN: 9784054017924

Leafhoppers are a general term for insects belonging to the family Cicadellidae, which are distributed worldwide and mainly inhabit the stems and leaves of herbaceous plants. At least 20,000 species have been described worldwide, and currently, 190 genera and 576 species are known in Japan, making them a highly diverse and thriving group. Planthoppers are closely related, but they can be easily distinguished by carefully examining their appearance. Spittlebugs are an even closer group, but their ecology is quite different, and they can also be distinguished morphologically by examining the structure of their hind legs. Like most true bugs, leafhoppers are herbivorous and survive by sucking sap from plants, so they pose little direct harm. However, species that feed on cultivated plants can cause significant damage due to their large populations. On the other hand, they are an important part of the food chain in ecosystems. The lives of leafhoppers are completely dependent on host plants and they lead very monotonous lives, but compared to closely related groups, their hind legs are longer, allowing them to crawl quickly sideways as their name suggests, and they are also active at night. The leafhoppers are also known for a unique substance called "brocosome," a hydrophobic coating used for various purposes. An interesting behavioral aspect is that in the subfamily Cicadellinae, both males and females communicate during courtship by vibrating stems. However, this is more of a means of recognizing one's own species than a female-led selection process like in birds or cicadas, and doesn't seem particularly romantic. The diversity of body color is the most striking feature when observing leafhoppers, but their evolutionary significance is lacking. Many are thought to be camouflage, but many are conspicuous. Some may function as Batesian mimicry, but this is not yet well understood. This article will explain the classification, morphology, and ecology of leafhoppers.

What is a leafhopper? How is it different from a planthopper?

From a taxonomic perspective, leafhoppers refer to insects belonging to the order Hemiptera, suborder Auchenorrhyncha, and family Cicadellidae.

The leafhoppers (Cithoptera) are a group of insects distributed worldwide, primarily inhabiting the stems and leaves of herbaceous plants. At least 20,000 species have been described globally, and currently, 190 genera and 576 species are known in Japan (Japanese Insect Catalog Editorial Committee, 2016). This makes them the second most diverse and thriving group in the order Hemiptera, after the aphid family.

What are the differences between species in the Cicadellidae family and their close relatives?

Planthoppers are closely related taxonomically and share similar habitats and ecologies, making them easily confused species.

However, in leafhoppers, the first and second antennal segments are only slightly thicker, whereas in planthoppers, the first and second antennal segments are very thick and conspicuous even from a distance (Hidaka et al., 1996).

Also, leafhoppers have heads that extend sideways, giving them a shape that resembles a "bent boomerang" when viewed from above, but planthoppers do not. However, there are exceptions, such as the lace planthopper.

It's also worth noting that planthoppers have a distinctive black spot resembling a pupil in their compound eyes, known as a "pseudopupil," but this is only a daytime feature.

From a taxonomic perspective, in leafhoppers, the simple eyes are located between the compound eyes, whereas in planthoppers, the simple eyes are located below or near the compound eyes (Ito et al., 1977).

There are other differences that can be observed by examining specimens in detail, but these will be omitted from this article.

What is the difference between a leafhopper and a spittlebug?

The spittlebugs are also very closely related to leafhoppers and look quite similar to them.

However, in the leafhoppers, the hind tibiae are long, angular with a raised line, lack large claw-like projections, and have numerous spiny hairs (often in two rows). The hind coxa are also long laterally, reaching the lateral margin of the ventral surface of the thorax and being plate-like.

In contrast, in the family Aesculitidae, the hind tibiae are short, cylindrical, and have one or two (rarely four) large claw-like projections on the outside. The hind coxa are also short, conical, and do not spread laterally.

It may be a little difficult to understand from a morphological perspective, but it's not difficult if you consider its relationship to ecology.

Because leafhoppers have long hind legs, they can "crawl" sideways, as their name suggests, walking horizontally on plants and quickly moving to the underside when disturbed. They can also jump like grasshoppers. In contrast, spittlebugs have short hind legs and cannot move in this way. The numerous spiny hairs of leafhoppers are used to coat plants with a hydrophobic substance called a "brocosome."

Also, although it's not apparent from the adults, the larvae of spittlebugs live in foamy masses or calcareous tubular nests they create on plant stems and branches. However, leafhoppers do not do this.

What do they eat? Are they harmful? Are they useful?

Like most true bugs, leafhoppers are herbivorous, primarily feeding by inserting their proboscis and stylet into the stems and leaves of herbaceous plants and sucking out xylem sap (a liquid mainly composed of water) and phloem sap (a nutrient-rich liquid produced by photosynthesis) (Hidaka et al., 1996). No species that feed on anything else have been identified.

However, it has been found that leafhoppers have a pair of symbiotic organs called "bacteriomes" on their abdomen, and that they receive essential amino acids from intracellular symbiotic bacteria (Koga, 2014; Tomizawa and Noda, 2014). This is thought to play a role in compensating for nutritional deficiencies caused by unbalanced diets.

While they can very rarely sting humans (Núñez & Aiello, 2013), there are few cases in Japan, and serious symptoms are extremely rare, so it's safe to assume that leafhoppers pose no direct harm.

However, leafhoppers that feed on cultivated plants are known to transmit diseases in addition to directly causing damage through feeding (Umetani & Okada, 2003; Emura et al., 2012). Because they are smaller than ordinary stink bugs and are more likely to be preyed upon, they employ a strategy of laying many eggs to increase their population (r-strategy), which is troublesome because they can proliferate in large numbers when the environment is suitable. Representative examples of leafhoppers that cause damage are listed below.

• The black-tipped leafhopper Nephotettix cincticeps feeds on rice plants and transmits infectious diseases such as rice dwarf disease (caused by the rice dwarf disease virus) and yellow dwarf disease (caused by phytoplasma) (Hokkyo, 1972).
• The lightning leafhopper Maiestas dorsalis (Recilia dorsalis is a synonym) feeds on rice plants (Matsumoto, 1988; Webb & Viraktamath, 2009).
• Jacobiasca formosana feeds on tea plants (Okada, 1971).
• Bothrogonia ferruginea feeds on the sap of many plants, including soybeans, peanuts, mulberry, tea plants, grapes, citrus fruits, persimmons, and figs, but in most cases, it does not cause significant damage (Ishihara, 1962; Umetani and Okada, 2003). However, in the case of mulberry, branch growth may be inhibited due to damage caused by sap feeding and egg-laying.

Hearing only these facts might lead one to emphasize only the harmful aspects to humans.

However, not all leafhoppers parasitize cultivated plants, and it is well known that they are an important food source for predators such as mirid bugs, water striders, parasitic wasps including stink bugs, spiders, and frogs (Nakasuka, 1977; Kobayashi, 1963; Handa and Sanda, 2018; Kosugi, 2003; Ono et al., 2004). These animals then become nutrients for higher-level predators such as birds and mammals.

It's also possible that certain plants are being suppressed from multiplying.

Therefore, from an ecological perspective, leafhoppers play a crucial role in the food chain, facilitating the transfer of nutrients from plants to animals. Leafhoppers are considered one of the most abundant herbivorous insects in grasslands, and in British grasslands, their population can exceed one million per hectare during the height of summer (Hamilton & Whitcomb, 2010). Similar situations are likely in Japan, and their influence cannot be ignored. While some species can be harmful, humans need to gain a deeper understanding of their importance.

What was its life history like? It lived an incredibly monotonous life on plants!?

The home range of leafhoppers is entirely dependent on their host plants (Hidaka et al., 1996). Species that are monophagous, which use only one type of plant as a host, or narrow-minded, which use several types of plants as hosts, live only in specialized environments. However, polyphagous species, which use host plants from multiple families, can live in a variety of environments.

At first glance, it might seem that being polyphagous is unilaterally advantageous, but monophagous insects are better able to cope with the unique structures and toxins of each plant species, and are also stronger in interspecies competition with polyphagous leafhoppers. Therefore, if the plants growing there are limited in variety, monophagous insects can be advantageous.

The life of that leafhopper is very monotonous.

Most of their lives are spent sucking sap from plants, and it has been found that in the case of the black-tipped leafhopper, 85% of the day is spent on sap-feeding.

Therefore, in a sense, it could be described as "a machine that simply sucks up plant sap."

However, because of their long hind legs, they can "crawl" sideways, as their name suggests, walking horizontally on plants and quickly moving to the underside when disturbed. Furthermore, they can jump like grasshoppers. This is something that their close relatives cannot do and is an example of their active behavior. These characteristics likely help them escape predators. However, in some species, when the environment stabilizes, a brachywing form appears in which the forewings and hindwings shrink and they are unable to fly.

Furthermore, they are often seen gathering around streetlights at night, and large numbers of leafhoppers appear when light traps are set up. This fact also indicates that leafhoppers actively fly and move between plants even at night, but the details of their activity at this time are difficult to study and are not well understood.

From a human perspective, their lifestyle may seem too monotonous, but compared to aphids that live similar lives, their bodies are clearly more developed, so perhaps that's not actually the case.

What is the role of "brocosomes," substances unique to the leafhopper family?

They are also known to secrete a substance unique to the leafhopper family called "brochosome." This substance is produced within the cells of a specialized glandular segment of the Malpighian duct, the main excretory organ of insects. Brochosomes are uniform, spherical particles, typically between 0.2 and 2.0 μm in diameter.

Brocosomes are released from the anus in droplets after molting, and are "oiled" all over the body by rubbing with the legs, spreading on the outer skin as a hydrophobic coating. Even after drying, brocosomes are applied to the entire body and legs by repeatedly grooming regularly.

The first thing that comes to mind is that this coating makes activities easier in the rain, but its functions are thought to be multifaceted (Rakitov, 2004).

The hydrophobic properties of brocosomes are effective not only against rain but also against their own liquid excretions. These excretions originate from the sugars in the sieve fluid, and their high viscosity can cause respiratory distress if they adhere to the spiracles, which are responsible for air intake and exit. Their viscosity would also slow down movement. Brocosomes prevent these situations.

It's also thought that these scales could serve a similar purpose to the scales of a lepidopteran spider, allowing it to escape if it gets caught in a sticky spiderweb.

Furthermore, it has been found to have functions such as protection from fungi (mold) and prevention of drying.

In some female species, not only do they store brocosomes themselves, but they also store them in their forewings before laying eggs. They have been observed rubbing the brocosomes onto the eggs with their hind legs after inserting them into plants.

The same reasons mentioned above are likely behind this use, but in addition, it is thought that when embedded in a plant, it prevents the plant from closing the wound, allowing the egg to breathe.

While this alone makes it highly versatile, recent research has shown that due to the anti-reflective properties of brocosomes, surfaces coated with brocosomes appear like leaves to the eyes of parasitic wasps and predatory insects, and are therefore also used as camouflage for eggs (Yang et al., 2017).

Romantic communication was conducted through "sounds" or "stalk vibrations"!?

Many male leafhoppers, like many other copopterans such as cicadas, are known to communicate through vocalizations (Davranoglou et al., 2020). However, although the mechanism is the same as that of cicadas, the sound is not as conspicuous, so it is generally inaudible to humans.

The vocal organ that produces this sound is also common to that found in many male copopterans, such as cicadas, and is called a "tymbal organ." It consists of a "tymbal structure" located outside the abdomen and a "tymbal muscle" located inside the abdomen (Iwamoto, 2018).

I can't go into the specifics of the pronunciation mechanism here, but simply put, sound is produced by stretching and releasing the vocal diaphragm with muscles.

This type of communication generally functions as a "courtship display," where the female selects her preferred male. Birdsong is a prime example of this.

However, it has been found that the leafhoppers of the subfamily Cicadinae and some other leafhoppers have developed a different form of "communication through vibration" (Hidaka et al., 1996; Davranoglou et al., 2020).

In the subfamily Cicadinae and some other leafhoppers , males and females communicate by vibrating their abdomens with these muscles, causing the stem to vibrate rapidly.

The interesting thing about this form of communication is that, unlike cicadas or leafhoppers with sound-producing membrane organs where it's a one-way communication from male to female, both male and female transmit vibrations to each other.

These leafhoppers have newly developed a "vibrating organ," also called the "typhlocybine organ." While they may sometimes retain both this typhlocybine organ and the sound-producing membrane organ, in the typhlocybine subfamily, the sound-producing membrane organ has degenerated and been completely replaced by the typhlocybine organ.

A unique feature of the organs of the leafhopper subfamily is that they are present in both males and females. They consist of plate-like internal projections (abdominal apodemes) on the ventral plates of the first and second abdominal segments, along with thick muscles, which vibrate the substrate, such as plant stems.

This vibrational communication occurs when males and females are facing each other at close range, as well as immediately before mating (Derlink et al., 2018). Therefore, even if it is not a one-sided courtship display by the male, it may still be considered to be used in some form of courtship display, like in other copopters.

However, it is now being suggested that a large part of the role of this vibrational communication is not courtship display, but rather "recognition of the same species."

It has been found that the frequency and intensity of vibrations differ among leafhoppers of the subfamily Cicadinae, and that they only respond to vibrations of the same frequency and intensity (Tishechkin, 2015; Derlink et al., 2018).

In other words, the meaning of communication through sound seems to have changed in leafhopper species that possess organs belonging to the subfamily Leafhopperinae.

While the exact reason isn't fully understood, in the case of the leafhopper, a major factor may be that its r-strategy allows for a very high number of breeding cycles, reducing the need for courtship displays. If they can breed frequently and produce many offspring, then carefully selecting a mate becomes a waste of time. Of course, the females simply lay eggs and leave them, so they don't have to worry about raising their young like mammals or birds.

In fact, the fact that males and females vibrate towards each other, and that there is often no difference in body color between males and females, is not characteristic of species that perform courtship displays, and experiments have shown that females do not distinguish between subtle differences in male vibrations (Hunt et al., 1992). These facts may indicate that females do not have a preference for males.

Interestingly, it has been observed that if another male is nearby a female receiving vibrations from another male, that male may also perform vibrations with the aim of disrupting the communication between the vibrating male and female (Derlink et al., 2018). However, while this could be interpreted as the disruptive male being superior to the vibrating male in the eyes of the female, it may be more natural to interpret it as simply aiming to disrupt the vibrations and stop the communication behavior.

While the term "romantic communication" might sound very romantic, in the case of the leafhopper, it can be said that this behavior is actually a result of pursuing rationality—finding the same species among many individuals—and it might be a good example of why excessive anthropomorphism is not advisable. However, in species where the males and females have clearly different colors and "sexual dimorphism" is well-developed, there remains the possibility that this has evolved into courtship behavior by males towards females.

After mating, the female inserts her pointed ovipositor into plant tissue to lay eggs. In some species, females store brocosomes in their forewings before laying eggs, and after inserting the eggs, they are observed rubbing the brocosomes onto the egg-laying site with their hind legs (Rakitov, 2004).

A single female is said to lay around 100 eggs, and in most species, their reproductive capacity allows them to go through several generations each year.

What are the roles of body shape and body color?

Leafhoppers exhibit considerable diversity in appearance and color, and their wings, in particular, can be quite colorful. What roles do these colors play?

Unfortunately, there is a lack of research from this perspective.

Generally speaking, leafhoppers that use grasses or sedges as hosts are long and slender with a streamlined shape, which is thought to help them be less visible to predators on the narrow leaves (Hidaka et al., 1996).

In terms of body color, the body and wings are often the same colors as plants, ranging from green to light brown, and their patterns are mottled or have vertical stripes, making them easily confused with plants (camouflage).

However, this alone doesn't explain everything. There are clearly some very colorful and eye-catching colors. Are there any advantages to using such colors?

While the reason is unclear, several possibilities come to mind.

First, if there is sexual dimorphism, where there is a difference in color between males and females, it is likely that the color is used by the male to attract females. As mentioned above, most leafhoppers do not exhibit sexual dimorphism, but there is a clear difference in wing color in the black-tipped leafhopper and the white-fronted leafhopper. In these species, competition among males for females is intense, and sexual selection may be at play, making the conspicuous coloration useful outweighing any disadvantages. However, there is no specific research on this.

It is also possible that some species, while non-toxic, employ "Batesian mimicry," mimicking poisonous insects. The black-tipped leafhopper (Coccinella septempunctata) has large black oval markings on its head, pronotum, and scutellum, which have been suggested to mimic the pupa of the poisonous ladybug Coccinella septempunctata (Yamazaki, 2010). At first glance, they may not look alike, but to a predator of similar size viewing it from the front, it resembles a pupa. While it is still unknown whether predators actually make this judgment, it is an intriguing hypothesis.

Furthermore, it's possible that they are actually poisonous and their coloration is a "warning color." However, while poisonous species have been identified in the closely related family Aesculitidae (Peck, 2000; Thompson & Carvalho, 2016), no poisonous species have been reported in the Cicadellidae family so far.

Coloration can have a significant impact both within and between species, but our understanding of it is still fragmentary, and further research is needed.

What kinds of species belong to the leafhopper family? How can they be identified?

Here, I will introduce the leafhoppers I have photographed so far, including specimens. If I find any misidentifications, I will change them without notice. The basic distribution is based on the Japanese Insect Catalog Editorial Committee (2016), and the morphology and ecology are based on Ito et al. (1977).

Although there are many species in Japan, there is little comprehensive identification data due to a lack of research. Regarding identification keys, there is "Illustrated Key to Homoptera and Cicadellidae" (Kamitani, 2013) in "Illustrated Guide to Insects 1: Comprehensive Edition of the Illustrated Key Series for Environmental Assessment Animal Survey Lectures," but it is difficult to obtain and will likely require a library photocopy. Regarding field guides, there is almost only "Illustrated Guide to Planthoppers, Leafhoppers, and Psyllids Commonly Found in Kyushu " (Saegusa et al., 2013). The rest must be supplemented with fragmentary materials. Identification up to the Cicadellidae family, and even up to the subfamilies of the Cicadellidae family, is possible with " Colored Illustrated Guide to Japanese Insects, Volume 2, Completely Revised New Edition " (Ito et al., 1977). However, the classification is outdated, so caution is needed. While the domestic and international photos found through Google Image Search are not always accurate, they can be very helpful when researching closely related species. We hope that simpler identification methods will become available in the future.

No. 03432 Citrus leafhopper Apheliona ferruginea (Leafhopper subfamily)

It is distributed in Honshu, the Izu Islands, Shikoku, Kyushu, Tsushima, the Osumi Islands, the Okinawa Islands, the Kerama Islands, and the Yaeyama Islands; as well as in China. In autumn, the adults gather on citrus fruits and suck the sap from the oil glands.

No. 03443 Austroasca vittata (Leafhopper subfamily)

It is distributed in Honshu, Kyushu, Tsushima; Korea, China, Russia, Mongolia, and the Palearctic region.

No. 03465 Bothrogonia ferruginea (Leafhopper subfamily)

It is distributed in Honshu, Shikoku, Kyushu, Tsushima, and the Osumi Islands; as well as in South Korea, China, Taiwan, Southeast Asia, and Africa (unclear). It may feed on the sap of many plants, including soybeans, peanuts, mulberry, tea plants, grapes, citrus fruits, persimmons, and figs, but in most cases, the damage is not significant enough to cause actual harm (Ishihara, 1962; Umetani and Okada, 2003). However, in the case of mulberry, branch growth may be inhibited due to damage caused by sap feeding and egg-laying. It has large black oval markings on its head, pronotum, and scutellum, which have been pointed out as mimicking the pupa of the poisonous seven-spotted ladybug Coccinella septempunctata (Yamazaki, 2010). At first glance, they may not look alike, but when viewed from the front by a predator of the same size, it resembles the pupa.

No. 03472 Large Leafhopper Cicadella viridis (Cicadella subfamily)

It is distributed in Hokkaido, Honshu, Shikoku, Kyushu, Tsushima, the Osumi Islands, South Korea, China, Russia, Vietnam, and the Palearctic region. It is common in grasslands and woodlands throughout these areas, parasitizing various plants and is known as a pest of many crops, including rice and tea plants.

No. 03479 Red Leafhopper Dayus takagii (Leafhopper subfamily)

It is distributed across Honshu, Kyushu, Tsushima, the Osumi Islands, the Amami Islands, the Okinawa Islands, as well as in South Korea, Taiwan, and China.

No. 03485 Spotted Leafhopper Diomma pulchra (Leafhopper subfamily)

It is distributed across Honshu, Shikoku, Kyushu, Tsushima, the Osumi Islands, the Amami Islands, the Okinawa Islands, and the Yaeyama Islands; as well as in South Korea, Taiwan, and China.

No. 03540 Evacanthus interruptus (Crested Leafhopper Subfamily)

It is distributed in the Kuril Islands, Hokkaido, Honshu, Shikoku, Kyushu, Korea, China, Russia, and the Palearctic region. It appears on Asteraceae plants in mountainous areas from July to August. The author reported the first record in Nara Prefecture (Ikeda, 2020).

No. 03569 Idiocerus yanonis (Leafhopper subfamily)

It is distributed in Honshu, the Izu Islands, Shikoku, Kyushu, Tsushima, the Osumi Islands, the Amami Islands, and the Okinawa Islands. The author reported the first record in Nara Prefecture (Ikeda, 2020).

No. 03582 Kolla atramentaria (Leafhopper subfamily)

It is distributed in the Kuril Islands, Hokkaido, Honshu, Shikoku, Kyushu, Tsushima, Amami Islands, Okinawa Islands, Kerama Islands, Miyako Islands, and Yaeyama Islands; as well as in South Korea, China, Russia, and Myanmar.

No. 03587 Horned Owl (Ledra auditura) (Owlininae subfamily)

It is distributed in Honshu, Shikoku, Kyushu, Tsushima, and the Yaeyama Islands; as well as in South Korea, China, the Russian Far East, and Taiwan. It has a pair of large ear-like projections on the posterior half of its pronotum; in males, these projections are slightly upward, but in females they are much larger and extend forward and upward. It camouflages itself by pressing its body tightly against branches to hide in the shade (Unno, 2019). Adults appear from around July, overwinter as adults, and the larvae parasitize beech family plants such as sawtooth oaks.

No. 03588 Short-eared Owl (Ledropsis discolor) (Owlininae subfamily)

It is distributed in Honshu, Shikoku, Kyushu, Tsushima, South Korea, China, and the Russian Far East. The head is long and protrudes forward in a bamboo-stalk shape, and the tip is not pointed. The protrusion is longer in females than in males. It camouflages itself by pressing its body tightly against branches to hide its shadow (Unno, 2019). It parasitizes Fagaceae plants such as Quercus glauca, Quercus acutissima, and Quercus serrata in plains and mountains, overwintering as a final-instar larva on tree branches, and adults emerge from around late April.

No. 03591 Limassolla multipunctata (Leafhopper subfamily)

It is distributed across Honshu, Kyushu, the Amakusa Islands, the Osumi Islands, the Amami Islands, the Okinawa Islands, the Kerama Islands, the Daito Islands, the Miyako Islands, and the Yaeyama Islands; as well as in China, Taiwan, India, and the Oriental region. It is common in broad-leaved trees and sometimes becomes a pest of mulberry and roses. Adults overwinter.

No. 03644 *Naratettix zonatus* (Leafhopper subfamily)

It is distributed in Hokkaido, Honshu, Shikoku, Kyushu, and the Yaeyama Islands; as well as in Korea, China, and Russia. It commonly inhabits various types of trees.

No. 03646 Nephotettix cincticeps (Caneliinae subfamily)

It is distributed across Honshu, Shikoku, Kyushu, Tsushima, the Ryukyu Islands, Taiwan, Korea, and the Philippines. In males, the wingtips (1/3) are black, while in females they are light brown. It frequently feeds on rice plants in paddy fields and transmits infectious diseases such as rice dwarf disease (caused by rice dwarf disease virus) and yellow dwarf disease (caused by phytoplasma) (Hōkyō, 1972).

No.03681.a A species of leafhopper, Pagaronia sp. (Subfamily Pagarinae)

Previously, the mulberry leafhopper Pagaronia guttigera was thought to be widely distributed throughout Japan, but it is now believed to be distributed only in Honshu (Kanto region) (Japanese Insect Catalog Editorial Committee, 2016), and the species corresponding to the individual photographed in Nara Prefecture is unknown. Numerous species are listed in "Japanese Insect Catalog, Volume 4: Neoptera," and as of 2008, field surveys have confirmed more than 140 undescribed species (new species) from the Japanese archipelago (Hayashi, 2008).

No. 03714 Penthimia nitida (Caneliinae subfamily)

It is distributed across Honshu, Shikoku, Kyushu, Tsushima; South Korea, China, the Russian Far East, and Taiwan.

No. 03720 Planaphrodes nigricans (Canelopinae subfamily)

It is distributed in Hokkaido, Honshu, Shikoku, Kyushu, Tsushima; as well as in Korea, China, and Russia.

No. 03751 Flat-headed Owl (Tituria angulata) (Owl subfamily)

It is distributed in Kyushu, the Osumi Islands, the Tokara Islands, the Amami Islands, the Okinawa Islands, the Kerama Islands, the Miyako Islands, the Yaeyama Islands, and Taiwan. The body is entirely yellowish-green, and the sides of the pronotum are flattened and angular. The larva is broadly ovate and extremely flattened. It camouflages itself by clinging tightly to branches and hiding in the shade (Umino, 2019). It parasitizes broad-leaved trees such as Ficus erecta.

No. 03768 Leafhopper Xestocephalus japonicus (Leafhopper subfamily)

It is distributed in Hokkaido, Honshu, the Izu Islands, Shikoku, Kyushu, Tsushima, the Amami Islands, the Okinawa Islands, the Kerama Islands, the Miyako Islands, and the Yaeyama Islands; as well as in South Korea, China, and the Russian Far East.

No. 03776 A species of leafhopper, Ziczacella sp. (Subfamily Ziczacellinae)

Identifying species of the genus Ziczacella requires examination of the male genitalia. Ziczacella hirayamella is distributed in Honshu, the Okinawa Islands, the Yaeyama Islands, Korea, China, and Russia. The author reported the first record from Nara Prefecture and confirmed its presence in the margins of deciduous broadleaf forests (Ikeda, 2020).

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