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One unlucky earwig

(or why you should not get attached to whatever you encounter in the wild)

Isn’t being outdoors the greatest thing in the world? Surrounded by the soothing beauty of nature, while observing species living together in harmony? It is easy to lose sense of reality sometimes. But things are not always what they seem, and this serenity is often deceiving. We do not like to think about it, but nature is a harsh environment. There is a constant struggle for survival, many animal and plant species compete with each other over resources and breeding space. In fact, many of the animals we humans encounter in the wild are already on their way out of the game, either due to senescence, diseases, pathogens or parasites. I always try to remind myself that if I stumble upon an elusive animal active beyond its normal activity time, and it is not startled by my presence, then something fishy is going on here.

That being said, I admit that many times my sound judgment is clouded by the sheer excitement of finding something I have never seen before. Case in point: During one of my visits to Mindo cloud forest in Ecuador, I came across a beautiful specimen of earwig.

Giant earwig (Allostethus sp.). Mindo, Ecuador

Giant earwig (Allostethus sp.). Mindo, Ecuador

In general, earwigs suffer from a bad reputation, or lack thereof. While many people simply ignore them because they do not find them interesting, others find them terrifying due to their menacing-looking pincers. Nevertheless, these animals are both fascinating and harmless. First, they have interesting behaviors. Pairs often construct a breeding chamber together, and females display maternal care, tending the eggs and baby earwigs until they can fend for themselves.

Giant earwig (Allostethus sp.) guarding the entrance to its burrow. Breeding pairs of earwigs construct such chambers, where the female later cares for the brood. Amazon Basin, Ecuador

Giant earwig (Allostethus sp.) guarding the entrance to its burrow. Breeding pairs of earwigs construct such chambers, where the female later cares for the brood. Amazon Basin, Ecuador

Second, earwigs cannot cause any injury to us. They cannot bite, and they possess no stinger or venom. Some species have an unpleasant odor, but you should not go sniffing animals that sport a pair of pincers anyway… Earwigs are omnivorous, and although they mainly feed on plant matter, they often use their modified cerci (the pincers) to manipulate soft prey such as moths and insect larvae. Earwigs are usually seen crawling on the ground or on plants, clumsily dragging their elongated body. However, they are also good fliers – underneath those square leathery forewings are neatly folded flight wings. During flight they spread like a delicate fan.

Detail of earwig wing. Ontario, Canada

Detail of earwig wing. Ontario, Canada

The earwig I found in Mindo belonged to the genus Allostethus (family Labiduridae). It is a beautiful animal, with a length of up to 35mm, a shiny black body and orange legs, and each of its forewings is decorated with a bright orange patch. I found it active on a mossy tree trunk in broad daylight, something I should have regarded to as suspicious, as earwigs are nocturnal insects. In any case, I did not give it much thought and collected the specimen, hoping I could later get some behavioral shots of it preying.

Giant earwig (Allostethus sp.), what a magnificent beast!

Giant earwig (Allostethus sp.), what a magnificent beast!

However, I waited too long. In the evening the animal stopped moving and appeared dead. I was devastated. It still looked healthy, no signs of injury, starvation, or poisoning. I decided to keep it in the vial and moved on to other work. The next morning I had my first evidence of the culprit – the earwig started to grow some whitish “fur”.

Giant earwig (Allostethus sp.) covered with entomophagic fungus. What a magnificent beast?

Giant earwig (Allostethus sp.) covered with entomophagic fungus. What a magnificent beast?

This was not, of course, fur per se, but small filaments indicating an infection by a parasitic fungus specifically feeding on insects. Parasitic entomophagic fungi (such as Cordyceps and Ophiocordyceps) are extremely common in the tropics. Moreover, they are so diverse that many of their species are host-specific. In other words, a certain fungus species attacks only arthropods from a specific order or family. Typically, the growing fungus inside the still-living arthropod alters its normal behavior, causing it to roam in unusual locations, and often outside of its normal range of activity hours. In many cases the infected animal climbs on nearby tree trunks, branches, or positions itself on the underside of a leaf. This is done to allow better spread of spores from the fungus fruit bodies.

Detail of the fungus feeding on the earwig

Detail of the fungus feeding on the earwig

Seeing that stunning earwig giving in and dying was heartbreaking, but it is important to remember it happens every day in nature. When walking in a tropical forest, there are signs of death by entomophagic fungi all over the place. It is hard to avoid corpses of ants, grasshoppers, moths, and beetles, all with bright fungal horns and tubers sticking out of their bodies. However, it is extremely hard to predict if a living arthropod is already infected with the fungus or not. Many times I have seen insects that behaved like “zombies”, only to later find out that they were harboring a parasitoid wasp or a parasitic worm. Looking for early signs of a fungus infection is trickier, but at least now I am a little bit wiser. I will know what to do the next time I see an earwig climbing up a tree at daytime.

Epomis beetles – insect response to amphibian tyranny

You can say that I am a little obsessed with Epomis beetles. Can you blame me? They are fascinating creatures. It suddenly dawned on me that since the launch of this blog I have not written a single word about the beetles. Unfortunately, there is a lot of misinformation and inaccuracies on the internet, and even in reputable magazines and books featuring Epomis.

It is one of the weirdest animal stories, one in which a small and seemingly harmless animal prevails against a much bigger animal. A unique case of predator-prey role reversal, where the would-be predator becomes the prey. Amphibians, such as frogs, typically prey on insects including ground beetles and their larvae. Among these beetles, one genus managed to stand out and deliver a proper counterattack to its predators. The Epomis larva has impressive double-hooked mandibles that look like they came right out of a horror movie. It waves them around along with its antennae until the movement attracts a hungry amphibian, which approaches quickly and tries to eat the larva. In a surprising turn of events, the larva is able to dodge the predator’s attack only to leap on the unsuspecting amphibian and sink its jaws into its flesh. It then continues to feed on the amphibian, sucking its body fluids like a leech at the initial stage, and eventually consuming it completely. Sounds like science fiction, I know. But it is real. Furthermore, these larvae feed exclusively on amphibians, and refuse to eat anything else. They are dependent on amphibian prey for completion of their development. This makes the predator-prey role reversal an obligatory one, which is very rare in the natural world.

First instar larva of Epomis circumscriptus showing its double-hooked mandibles.

First instar larva of Epomis circumscriptus showing its double-hooked mandibles.

I first learned about Epomis beetles in 2005, when I was working in the Natural History Collections at Tel Aviv University in Israel. They ended up being a great topic for my M.Sc thesis research, and I continue to study them to this day. The genus contains about 30 species distributed in the old world, with the African continent as the center of diversity. They inhabit the banks of rain-pools and temporary ponds, and synchronize their breeding season with amphibians’ metamorphosis into the terrestrial stage. Most of what we know about Epomis comes from studying three species only (in other words, there is more unknown than known). When the main paper from my thesis was published in late 2011, it became an instant hit in the media (see below). However, one main point of criticism was that the supplementary videos showed the interactions between Epomis and amphibians in a lab setting, which might have triggered an unnatural behavior from both. This is a valid point. We needed a controlled environment to test and prove beyond disbelief several hypotheses regarding the feeding habits of Epomis. Nevertheless, I spent the following years going back and recording the same interactions in the field.

Here is a larva of Epomis circumscriptus displaying luring behavior while waiting for a passing amphibian:

And this is the outcome of the above scenario:

 

To better understand what is happening during this swift encounter, here is a break down of this interaction to several simple steps. As you can tell by the above video, this sequence takes only a split second in real-time:

From enticement to desperation: European green toad (Pseudepidalea viridis) being lured to hunt and getting attacked by a larva of Epomis dejeani. View large!

From enticement to desperation: European green toad (Pseudepidalea viridis) being lured to hunt and getting attacked by a larva of Epomis dejeani. View large!

The larvae are terribly good at this. Even if they are caught by the amphibian’s tongue, they are still able to quickly use their mandibles to grab the amphibian from the inside, whether it is the throat or stomach, and start feeding.

Hard to believe, but this toad is being eaten.

Hard to believe, but this toad is being eaten.

Sometimes the amphibian accidentally steps on the Epomis larva. In this case, the larva will attach to the leg. First instar larva of Epomis dejeani feeding on a Lemon-yellow tree frog (Hyla savignyi).

Sometimes the amphibian accidentally steps on the Epomis larva. In this case, the larva will attach to the leg. First instar larva of Epomis dejeani feeding on a Lemon-yellow tree frog (Hyla savignyi).

While the larvae are specialized amphibian ambushers, the adult Epomis beetles are somewhat more generalist predators. They prey on other arthropods and will sometimes go for the occasional earthworm. But these feeding habits only last until they stumble upon an amphibian again. Then, a hidden memory back from the days they spent as larvae kicks in, and they set out to relive their glory days as amphibian slashers.

Epomis dejeani attacking a European green toad (Pseudepidalea viridis) while holding firmly to avoid falling off. Compare to the photo of the larva attached to the leg above.

Epomis dejeani attacking a European green toad (Pseudepidalea viridis) while holding firmly to avoid falling off. Compare to the photo of the larva attached to the leg above.

In a blink of an eye, the beetle sneaks up on the amphibian and pounces on it, holding firmly to avoid falling off. It then moves to the back, and like scissors uses its mandibles to make a horizontal incision, which disables the hind legs and ultimately prevents the amphibian from escaping. As if this was not gory enough, both adult beetles and larvae are particularly fond of eating the amphibian’s eyes. It is like a sick twist of revenge for the insects: after millions of years of suffering under the constant threat of predation by amphibians, they are able to fight back. Not only they hunt their potential predators and slowly eat them alive, but they also cripple them and peck their eyes out right from the start.

Remains of a partially eaten amphibian in the vicinity of temporary ponds are usually a good sign for adult Epomis activity in the area. Central Coastal Plain, Israel

Remains of a partially eaten amphibian in the vicinity of temporary ponds are usually a good sign for adult Epomis activity in the area. Central Coastal Plain, Israel

Epomis dejeani guarding a recently captured European green toad (Pseudepidalea viridis). The beetles can get very territorial over prey items.

Epomis dejeani guarding a recently captured European green toad (Pseudepidalea viridis). The beetles can get very territorial over prey items.

How did this phenomenon evolve? To be honest, we do not know exactly. But it is possible that somewhere in the evolutionary past, Epomis beetles used counterattack behavior, instead of escaping, as a defense against amphibians. Such behavior could have later evolved into exploiting amphibians as a source of food. The amphibians probably could have not evolved to recognize and avoid this behavior because the majority of insect prey they encounter poses no threat to them, as opposed to the relatively uncommon Epomis beetles. Another interesting point, is that both adults and larvae of Epomis lack any venom, yet the amphibian is quickly subdued and stops resisting after being caught, even while it is slowly being devoured alive.

One common reaction that I get in response to this study is that it was “cruel”, involving poor helpless amphibians that were sacrificed in the name of science. Some people even go further to suggest that I am a sadistic scientist somehow enjoying this. It could not be farther from the truth: This is a natural phenomenon and Epomis beetles must kill and consume amphibians in order to exist. Nature is cruel. We tend to think of amphibians as cute and helpless animals, but from the insects’ perspective they are actually cold-blooded killers (pun intended), gulping every small creature in their path. Moreover, the reality of this study is even harsher: the amphibians would have still died even without me using them as food for Epomis, because the puddles they were found in as tadpoles were quickly drying out. As for myself, I cannot begin to describe the emotional stress I suffered during this research, just so I could bring Epomis’ fascinating biology to the spotlight. I love amphibians, and it was disheartening for me to watch them die so many times. Throughout the study I kept telling myself: “I am going to hell for this, no doubt about it”.

In the past few years I have been following the response to the story of Epomis beetles. More sightings of the beetles are being reported from around the world. There are some excellent blog posts (1,2,3,4, and do not miss Bogleech!), news reports (1,2,3,4,5), videos and TV segments, radio interviews and podcasts, and even Wikipedia pages. Epomis has found its way into artwork. There is a metal band named after the beetles. It is very possible that this is the discovery I will go down in history for, and that is fine by me. Hollywood, I am waiting by the phone for your call. To end this post on a positive note, here is a fitting limerick that I love, written by the talented Celia Warren:

Of the genus Epomis, folk say,
Their larvae at first seem like prey,
But they’ll bite a frog’s throat,
Leave it paralyzed, note!
Then they’ll eat it without more delay.

Nailing that Megarhyssa shot – it’s all about flexibility

It is intriguing that I do not post much about North American insects. In fact, ever since I moved to Canada I became more and more obsessed with animals found in my home country (Israel). Some might say this is a common case of “you don’t know what you’ve got till it’s gone”, but this does not mean that North American insects are not exciting or interesting. On the contrary, there are many insect species I hope to see in person. One of these insects rewarded us with its presence during a day trip to Hilton Falls Conservation Area in Ontario. I thought I should write about it and share a little bit of the process of photographing it.

Giant ichneumon wasps (genus Megarhyssa) are some of the biggest North American wasps thanks to the females’ long (10cm) ovipositor, which is longer than the wasp’s own body. These wasps might look fierce but they are actually shy and harmless insects. They are parasitoids: their larvae develop as parasites living inside the body of other insects. The female’s ovipositor is therefore not a stinger, but an organ used to inject eggs into the larva’s host.

During our trip we came across an egg-laying female of Megarhyssa macrurus. I only had a couple of small lenses with me and no dedicated macro equipment, but still, I did not want to miss an opportunity to photograph a Megarhyssa during oviposition. I tried to go for a simple wide-angle macro style first:

Wide-angle photo of a female giant ichneumon wasp (Megarhyssa macrurus) during oviposition.

Wide-angle photo of a female giant ichneumon wasp (Megarhyssa macrurus) during oviposition.

Very quickly I ran across one of the problems I mentioned in this post. The wasp is so thin and delicate and easily gets “lost” in the background, even when it is slightly out-of-focus. To get a better result, I started to cut broad leaves and placed them like tiles in the background. This photo was taken with the same, non-macro lens as above. Surprising result!

Female giant ichneumon wasp (Megarhyssa macrurus) drilling in wood to lay eggs

Female giant ichneumon wasp (Megarhyssa macrurus) drilling in wood to lay eggs

Megarhyssa wasps attack the larvae of another wasp, Pigeon horntail (Tremex columba), which bore into dead wood. The female can detect tiny vibrations coming from inside the wood by the feeding horntail larvae. She then proceeds to egg-laying: she bends her abdomen, exposing her ovipositor from its flexible sheath, and starts drilling. When she reaches a horntail larva, she sends an egg all the way down the ovipositor and injects it to the host. The parasitoid wasp larva feeds on the host and kills it, and then pupates inside the wood. The new generation of Megarhyssa wasps will emerge as adults in the following summer.

Back to the process of photographing – The next thing I wanted was to test the flexibility of the lens (I always recommend doing this), so I took a few more “creative” shots at different angles. What I like about this photo is that you can also see some of the previous holes this female drilled using her ovipositor.

Giant ichneumon wasp (Megarhyssa macrurus) injecting eggs into horntail wasp larvae found inside dead wood

Giant ichneumon wasp (Megarhyssa macrurus) injecting eggs into horntail wasp larvae found inside dead wood

The last goal was to get a dreamy background, showing some of the light entering through the canopy. This was a bit tricky, because the wasp was facing down towards the ground. Since I do not have special equipment (such as an angle-viewfinder or a tilt-screen), I had to be creative and improvise. Unknowingly, I had my photo taken while trying to compose the shot. I was completely unaware of my pose because I was too focused on photographing, and I guess some of the poses I tried might have been embarrassing for my trip partners… To tell the truth, I had no idea my body was even capable of getting into these positions. If you look closely, you can even see the wasp in this photo, it is very big!

Flexibility is important while photographing insects!

Flexibility is important while photographing insects! Photo by Mio Konfedrat.

After much bending and neck-twisting I managed to get the shot that I wanted:

Female giant ichneumon wasp (Megarhyssa macrurus) in egg-laying

Female giant ichneumon wasp (Megarhyssa macrurus) in egg-laying

Nice to cross this incredible species off my “wanted” list.

Giving birth to a botfly

Sitting at my dentist chair for 40 minutes and suffering through the shrill sound of the ultrasonic cleaner, I suddenly started to feel contractions from my chest. Oh, no. Not now. Is it really happening? If it happens now this will be a visit I will never forget. Am I getting into labor?

2014 hit me hard in the face with all its goodies, that it was difficult for me to pinpoint the best moments. I still have one more story to share before I bid farewell and move on. For me, 2014 ended with a blast.

The story actually begins in fall 2013. Shortly after returning from BugShot Belize, I noticed that three mosquito bites on my chest were not going away. They became red, started to feel even itchier, and occasionally there was a slight pinprick sensation. I immediately suspected they harbored botfly larvae, and indeed confirmed this after a couple of days when the sensation became more intense.

Hypoderma bovis is a species of botfly that attacks cattle. The resemblance to a bumblebee is not incidental. Upper Galilee, Israel.

 

Botflies belong to the family Oestridae, whose larvae develop in the body of mammals as endoparasites. They are mostly known as pests of cattle, but also of rodents and other small mammals. At least one species, Dermatobia hominis, attacks primates and, as I learned the hard way, humans. And it does this in the most incredible way: the female botfly waits in ambush for a female mosquito to pass by, and when the blood-sucking insect shows up, a chase ensues between the two. The botfly grabs the mosquito in mid-air and takes her captive to the ground level, where she proceeds to do something unique to Dermatobia botflies – she starts to lay eggs under the abdomen of the now-immobilized mosquito. When she is done, she releases the mosquito from her grasp. Now the botfly has a carrier, a vessel to transport the eggs to a suitable host, preferably a mammal. Once the female mosquito locates a bloodmeal and lands in order to bite, the mammal’s body heat triggers the botfly eggs to hatch, and tiny larvae drop to the mammal’s skin. They quickly start to burrow into the skin, head in first. Some take advantage of existing pores, such as hair folicules or even the mosquito bite itself. The small larvae have several rings of curved hooks pointing backwards; these hooks assist in anchoring the larva inside the host’s tissue and prevent removal. After fully embedded into the mammal’s flesh, the larva (which is a foreign object) excites the body’s immune system, and feeds on the inflammation response and white blood cells that arrive to the area. Its only connection to the outer world is through the entrance hole, now called punctum, from which it extends its spiracles for breathing air.

This beautiful mosquito (Psorophora sp.) is known to be one of the vectors for D. hominis eggs. Photographed in Belize, in the same location where I got my botfly larvae.

 

When I first learned about Dermatobia hominis in Intro to Entomology course back in 2004, I could not help but wonder how it feels to have an insect living inside one’s body; whether it is painful; and does it show on the outside? Little did I know that I would become a host for the same species 10 years after. Well, it was painful indeed. Sharp, ticking pains that came and went in cycles. I immediately sought medical advice and came across a medical paper describing a method for removing botfly larvae using a suction pump. Fortunately for me, the leading author of the paper was a bus drive away. There was much excitement at the Tropical Diseases Clinic, when several doctors and medical students gathered to see my botflies. We removed three tiny larvae, and I was released home. Then, in the evening of the same day, I felt that sharp pain again from all three locations. Over the next days, the pain became worse, think of chest-stabbing, or corkscrewing in pulses with heated iron and you get the idea. There were larvae still in there. And it seemed they were growing faster because there was no competitor in there with them (the larvae we already removed). To make a long story short, I managed to remove one of these larvae (on Halloween Eve nonetheless!), accidentally killed another at the clinic (only to be removed later by me), and failed to remove the third one. It continued to remind me of its existence with pseudo heart attacks several times every night until it finally died and the punctum sealed over it.

This was quite the experience, and we even published a report of the case in a medical paper. Originally, I wanted to keep one of these larvae until completion of its development. As an Entomologist, I was eager to see the adult fly, let alone this might be the only chance I could give something in return after collecting and killing many insects for my scientific work. However, I was not lucky, and I started to accept the possibility that I will not get another botfly larva, surely not in such a convenient location again. And so, a year later I returned to Belize, not even considering the option that it might happen again. Remembering the lancinating pain that I experienced, I tried to be careful and well-protected from mosquitoes this time. So you can imagine my surprise after I returned home, when I found a new botfly larva in my chest, almost in the same location as last year!

At first I repeated the “routine” of visiting the Tropical Diseases Clinic, but the larva was still too small to be removed. Then I decided to leave the area as is and give the larva the space it needs. I was amazed to find out this larva was not even slightly painful. The feeling was completely different, I could easily feel it moving, but there was no discomfort about it. This is it. I am keeping it.
Maybe I should pause here and say that a botfly is probably the “friendliest” parasite one can wish for. It does not transmit any diseases, does not cause any significant damage to the body, does not leave any scars, keeps its area clean from infections by antibiotic secretions and most importantly – unlike other parasites, once it finishes doing its thing, it leaves on its own!

Portrait of human botfly (<em>Dermatobia hominis</em>) larva. The resemblance to a walrus is incidental.

Portrait of human botfly (Dermatobia hominis) larva. The resemblance to a walrus is incidental.

 

For more than two months I nurtured the larva, patiently observing while it was growing inside me. Photographing it was not easy, and essentially could only be done facing a mirror, but I learned the trick and eventually got used to operating the gear backwards. It allowed me to take this photo of the larva’s spiracles as it is breathing from the punctum (this might be graphic to some people, so you can view it here). But like I said my real goal was to see the adult fly, and I was restless in the final two weeks of the larval development in fear that I will miss the event. The botfly larva does not pupate inside the host. It first has to leave its host’s body, drops off to the ground and then quickly looks for a suitable place for pupation. In the end, the contractions I felt at the dentist were a false alarm, and I could not feel anything when the larva emerged eventually.

Human botfly (Dermatobia hominis) larva after emergence from its host, searching for a place to pupate.

Human botfly (Dermatobia hominis) larva after emergence from its host, searching for a place to pupate.

 

Incubating the puparium has to be the hardest part in keeping a human botfly. In a fascinating paper from 1930, Lawrence H. Dunn describes how he deliberately allowed two botfly larvae enter his arm to document their development. Only later he found out that prior to his actions he was already infected with four additional larvae (on his other arm and leg). The paper is not an easy read, as it spans through the various sensations and types of pain the author experienced during this period. Eventually he had all his six larvae emerging as late third-instars, pupating and turning into adult flies. Unfortunately, this last part of the paper is poorly written and lack details. How moist was the pupation substrate and what was its composition? Did the larvae burrow or stayed on its surface? How long after emergence the adult flies started activity? And were there any losses during the pupation period? That last question is extremely important because I have heard of many failures in keeping Dermatobia hominis for the purpose of getting adults, and they mainly happened during the pupal stage. This is why I was so thrilled to find the adult fly one afternoon waiting in the container. What a great ending to 2014. And what a magnificent fly it is! Glowing red eyes, a pointy head with a bright silvery “face”, and the most dazzling blue abdomen, striking with metallic gloss. For me, this was literally the miracle of birth. No matter how I look at it, this fly is my own flesh and blood.

Human botfly (Dermatobia hominis) adult, fresh after emergence from its puparium (left)

Human botfly (Dermatobia hominis) adult, fresh after emergence from its puparium (left)

 

Larva and adult of the human botfly (Dermatobia hominis). Hard to believe this is the same animal.

Larva and adult of the human botfly (Dermatobia hominis). Hard to believe this is the same animal.

 

Totally worth it.

 

In this day and age, even a fly can take a selfie.

 

Was it worth it? Absolutely.

Piotr Naskrecki had his own personal experience bringing (two!) botflies to adulthood. You can read his blog post here. And do not miss the postscript!

UPDATE (12 Jan, 2015): Piotr has just posted a video about his botfly. Please go to his blog and watch it. I cannot recommend it enough; this is most likely the only filmed documentation that follows the botfly throughout its development to adulthood in a human host:
http://thesmallermajority.com/2015/01/12/dermatobia-redux/
Thank you everyone for the positive response to this story!