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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 (Bufotes viridis) being lured to hunt and getting attacked by a larva of Epomis dejeani. View large!

From enticement to desperation: European green toad (Bufotes 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 (Bufotes 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 (Bufotes 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 (Bufotes viridis). The beetles can get very territorial over prey items.

Epomis dejeani guarding a recently captured European green toad (Bufotes 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.


UPDATE (8 Feb, 2018): I decided to add a gallery page dedicated to Epomis beetles. You can find it here.

Meet Your Neighbours

I recently joined as a contributor to Meet Your Neighbours – a global photography project that sets out to connect communities with their local flora and fauna, and promotes nature conservation. The idea is to record all possible biodiversity against a clean white background using a simple field studio. By stripping the subjects off their natural surroundings they become the center of attention, provoking more interest. Another benefit from photographing against a white background using a standard protocol is that all subjects from different parts of the globe get the same level of appreciation, regardless of their location or taxonomic group. This can reveal interesting patterns: when comparing subjects from different origins it is difficult to say which is more exotic. In other cases, subjects that are physically very distant from each other share many similarities in appearance.

Ocellated Skink (Chalcides ocellatus) modeling for me on the white backdrop

Ocellated Skink (Chalcides ocellatus) modeling for me on the white backdrop

 

Checkered beetle (Trichodes affinis) is very common on Asteraceae inflorescence during the Israeli spring

Checkered beetle (Trichodes affinis) is very common on Asteraceae inflorescence during the Israeli spring

 

I discovered Meet Your Neighbours in 2010 and was immediately hooked. I liked this style of photography, which reminded me of old natural history books featuring illustrations of plants and arthropods. At that time I was already trying to achieve similar results in my photography, only I was using white paper as background so the effect was a bit different. For this reason I was delighted and honored when Clay Bolt, one of MYN founders, contacted me in 2013 with the offer to join the project. For me this meant one main goal – presenting species from Israel, even though I am based in Canada and travel quite extensively to other countries.

Mediterranean House Gecko (Hemidactylus turcicus)

Mediterranean House Gecko (Hemidactylus turcicus)

 

Darkling beetle (Erodius gibbus). This is perhaps the most easily recognized beetle in Israel (after the overrated ladybug). Its small size, oval shape, and matte back color are unmistakable. This species also has a wide distribution range in sand dunes along the Israeli coast, and it can be found in the desert as well.

Darkling beetle (Erodius gibbus). This is perhaps the most easily recognized beetle in Israel (after the overrated ladybug). Its small size, oval shape, and matte back color are unmistakable. This species also has a wide distribution range in sand dunes along the Israeli coast, and it can be found in the desert as well.

 

Israel is located at the bridge of three continents – Europe, Asia and Africa. Due to its geological history and a variety of ecological conditions, Israel is characterized by a climate gradient from north to south, and to some extent from west to east. This creates many habitat types throughout the country, which are home to an impressive diversity of animals and plants. Most species in Israel are typical to the Mediterranean region, but desert species can be found in south of the country, whereas species from colder origins like Europe and Asia are found in northern Israel. For the latter Israel is the southernmost point in their distribution. Some species of tropical origin can also be found in the oases along the Great Rift Valley.

I decided to start my contribution to MYN from the very base, the creatures I know well from the places I explored as a kid.

The semi-stabilized sand dunes of Israel are home to the beautiful ground beetle Graphipterus. A recent study revealed that instead of the single species G. serrator, there are actually three similarly-looking Graphipterus species in Israel, each with its own distribution. This beetle, from the Central Coastal Plain, seems to be a new species to science and is currently being described.

The semi-stabilized sand dunes of Israel are home to the beautiful ground beetle Graphipterus. A recent study revealed that instead of the single species G. serrator, there are actually three similarly-looking Graphipterus species in Israel, each with its own distribution. This beetle, from the Central Coastal Plain, seems to be a new species to science and is currently being described.

 

I grew up in a city in the Central Coastal Plain of Israel. I had the fortune of spending my childhood with a lot of nature around me. Wildflower fields, Citrus orchards, temporary ponds and sand dunes were at walking distance from my house. Every weekend I would go out in the morning and get lost somewhere in the wilderness, looking for interesting animals. And there was much to be discovered: tame snakes, skinks, beautiful insects like beetles and mantises, frogs and spiders. I used to rear butterflies in my room because I was fascinated with the transformation from a caterpillar to the adult butterfly. I am still fascinated by this metamorphosis even today, although I focus on other insect groups.

This spring, I took a short research trip to Israel, and used this opportunity to document some of my favorite animals. I hope that through these photographs people can learn more about the diversity of the country and maybe in time will even consider visiting!

Isophya savignyi, a common flightless katydid from Israel. Top - male; bottom - female

Isophya savignyi, a common flightless katydid from Israel. Top – male; bottom – female

 

Mediterranean banded centipede (Scolopendra cingulata), one of the most commonly encountered arthropods under stones in the Central Coastal Plain during the spring season

Mediterranean banded centipede (Scolopendra cingulata), one of the most commonly encountered arthropods under stones in the Central Coastal Plain during the spring season

 

Compsobuthus schmiedeknechti, one of the smallest scorpion species in Israel. This adult female is only 3cm long, including the tail!

Compsobuthus schmiedeknechti, one of the smallest scorpion species in Israel. This adult female is only 3cm long, including the tail!

 

I was very fortunate to meet one of the most charming reptiles in Israel: the Mediterranean Chameleon (Chamaeleo chamaeleon rectricrista). Every encounter with a chameleon is always a splash of spectacular coloration and behavior. This individual was very cooperative and returned to its perch after the photo shoot.

I was very fortunate to meet one of the most charming reptiles in Israel: the Mediterranean Chameleon (Chamaeleo chamaeleon rectricrista). Every encounter with a chameleon is always a splash of spectacular coloration and behavior. This individual was very cooperative and returned to its perch after the photo shoot.

 

BugShot Belize: Treat yourself to something good

I have been meaning to write about BugShot Belize straight after my return, while I was still excited about it, but upcoming deadlines and a small entomological ordeal took most of the attention.
But don’t get me wrong – whenever I think about this trip to Belize I get a huge grin on my face. It was THAT good.

If you have some interest in macrophotography, you probably heard about the BugShot workshop series – a get-together of photography and arthropods enthusiasts, over the course of several days, led by some of the best macrophotographers out there.
The notice about an upcoming workshop in Belize caught me while I was conducting my research fieldwork in New Zealand. I was thrilled to hear there would be four instructors instead of three: Alex Wild, Thomas Shahan, John Abbott, and, joining them for the first time, Piotr Naskrecki. I knew I had to secure my place in that workshop.

By the way, do not mistake this for an in-depth review of BugShot. This post is not going to be a list of what we did during the workshop. If you search online, you will find several such reports. I believe that if you consider going to one of these workshops, you should stop reading about them online and start working on getting there yourself. I will, however, highlight a few things that made the whole experience worthwhile for me.

I came to BugShot Belize with three main goals: to improve in taking photos in high magnification, to learn more about wide-angle photography, and to hear about high-speed photography.

Leafcutter ants (Atta cephalotes) carrying a leaf as food source for mushrooms cultivated inside their nest. These ants almost never stand still, and require some concentration to photograph. In addition, some backlighting helps to make the leaf "pop out".

Leafcutter ants (Atta cephalotes) carrying a leaf as food source for mushrooms cultivated inside their nest. These ants almost never stand still, and require some concentration to photograph. In addition, some backlighting helps to make the leaf “pop out”.

 

We stayed at Caves Branch, a beautiful Lodge set in the middle of the Belizean jungle. The owner attended one of the earlier BugShots, so we were lucky to have the best host one can ask for. Although being acquainted with only one other person before the workshop, I immediately felt connected to everyone else.

One of the questions I was repeatedly asked during the workshop was “is any of this new to you?”, and I have to say I found it a bit odd at first. I am not known as a photographer and at that time I had only a handful of photos uploaded to this website. But then it hit me – I do have some experience in photography (I started the photography hobby when I was 14, so I must have learned a thing or two since then), and I do have background in Entomology. Nevertheless many things were new to me – every person brings his own approach to photography and for being out in nature. It was interesting to listen to both the instructors and the people attending the workshop. In fact, here I feel I need to apologize before my fellow BugShotees (and anyone else I might meet in the future) – Most of the time I am quiet and I do not strike as being a very talkative person. But once I “break-in” I do not cease talking, and unfortunately I can get a little annoying then. So I apologize if I never interacted with some of the people, or was simply impossible to shut up when talking with others.

We had a small light trap to attract flying insects at night, which proved quite promising in the first night when we had no clue what to expect. One of the moths that arrived was so adorable that it led to a collaborative post with Nash Turely, who recorded a hilarious video of the moth settling into its resting pose.

Periphoba arcaei (Hemileucinae) aka bunny moth. Cute furry legs!

Periphoba arcaei (Hemileucinae) aka bunny moth. Cute furry legs!

 

Periphoba arcaei (Hemileucinae) employs a defense posture when camouflage fails, revealing aposematic colors to scare off predators.

Periphoba arcaei (Hemileucinae) employs a defense posture when camouflage fails, revealing aposematic colors to scare off predators.

 

But the main highlight for me was not waiting for the insects to come, but being able to go on night walks in a tropical jungle and actively search for whatever I could find. Man, how I missed doing this! If you like nature but have never done it, I highly recommend! Just be aware of all the possible dangers lying ahead and care for you own safety. And DO NOT do this alone, especially at night (speaking from personal experience, you can easily get lost).

A juvenile whipspider (possibly Phrynus parvulus) feeding on a caterpillar, found during a night walk.

A juvenile whipspider (possibly Phrynus parvulus) feeding on a caterpillar, found during a night walk.

 

Let’s get back to my goals though. Unfortunately, I did not give myself too many opportunities to photograph in high magnification. There were so many things to see and photograph in the jungle, that very often I found myself making the mistake of sticking with one lens throughout most of the day just for the sake of not missing a subject. In addition, the intense humidity made it very annoying to switch lenses because they would fog up very quickly.

Portrait of an assassin bug (Reduviidae) in the rain

Portrait of an assassin bug (Reduviidae) in the rain

 

Scales on hindwing of an owl butterfly (Caligo sp.) - it reminded me of a tiger!

Scales on hindwing of an owl butterfly (Caligo sp.) – it reminded me of a tiger!

 

One of the techniques I was eager to know more about was wide-angle macrophotography, and you can image my excitement when I realized I could learn it from one of the best. Good thing I was not lazy and decided to bring my tripod.

Piotr Naskrecki explaining about wide-angle macrophotography

Piotr Naskrecki explaining about wide-angle macrophotography

 

This was my first attempt to shoot wide-angle macro in BugShot:

Female canopy katydid (Tettigoniidae) resting on a Heliconia leaf

Female canopy katydid (Tettigoniidae) resting on a Heliconia leaf

 

It is OK, but could be better. Apparently I was doing a few things incorrectly, which led to a poor composition and lighting in the photos.
And below is the photograph I took while learning from the master, Piotr Naskrecki. Some people might actually prefer the previous photo. I like this one much better.

Leaf-mimicking katydid (Mimetica sp.)

Leaf-mimicking katydid (Mimetica sp.)

 

Of course, in these techniques, practice makes perfect. There is still plenty of room to improve. But I am slowly getting there.

Apart from some interesting arachnids that we found, the best find in my opinion was a tiny scarab beetle (Ceratocanthinae, identified as Ceratocanthus sp. by Dr. Alberto Ballerio) that can roll into a ball. Unfortunately, I did not take a photo while the beetle was open and moving about. If anything, this is a good reason to go back to Belize, I think this animal is incredible. I have known rolling isopods, pill millipedes, pill roaches, even some flies and wasps evolved to roll up into the shape of a sphere for protection from enemies, but this animal was something that was completely new to me. This beetle is so tightly packed when rolled-up, every leg is inserted into a dedicated slot, that it almost looks like a transformer.

Pill scarab beetle (Ceratocanthus sp.)

Pill scarab beetle (Ceratocanthus sp.)

 

But my all-time favorite photo from the workshop was not of an insect (well, not entirely). One of the people who attended the workshop was Roy Dunn, an acclaimed photographer specializing in high-speed photography (and an avid arachnophile). I enjoyed listening to his and John Abbott’s comments about this technique, and we were lucky to have the opportunity to get a hand-on experience with it. While I was impressed with Cognisys demonstration, I was more interested in controlling the light using few accessories as possible while taking high-speed photos. When we visited a nearby butterfly farm we could not take our eyes off the stunning hummingbirds coming to feed on sugar water. Many people tried to photograph them from up close using a flash (to whom Roy remarked: “That’s not how you do it!”). Although macro shots of hummingbirds can be amazing, the flash created a harsh light. So I tried to photograph in ambient light using my telephoto lens (Canon 500mm) with no flash, playing with the settings in the camera. Carefully framing to get the light reflected behind the birds, I ended up with some impressive shots, one of them is clearly my favorite of all my BugShot portfolio. Actually, I consider it to be my best photo from 2013. And it even has an insect in it.

Rufous-tailed Hummingbirds (Amazilia tzacatl) and a paper wasp passing by

Rufous-tailed Hummingbirds (Amazilia tzacatl) and a paper wasp passing by

 

So my tip to you: if you have any interest in small creatures (they do not have to be insects!), and you like to photograph, go to one of these workshops. It does not matter if you are an amateur or a professional. Even if you think you have enough photography experience I still recommend attending – just being around people who share similar interests might spark you to try something new. There is already a new BugShot Belize workshop planned with similar content and instructors. If you read this far, you probably want to be there.

Don’t mess with the Huhu

On my first night in New Zealand, I did something that I always do when I get to a new place – see which insects were attracted to light that was left on. The usual suspects are various species of moths, but sometimes also katydids, antlions and beetles.

To my surprise, the first insect that I found was a large longhorn beetle (family Cerambycidae). With a length of 50mm, hairy body, large mandibles and beautiful elytra reticulated in yellow, one could not miss it resting on the asphalt. I later learned that this was the huhu beetle, Prionoplus reticularis, New Zealand’s largest endemic beetle.

The huhu beetle, Prionoplus reticularis

The huhu beetle, Prionoplus reticularis

Detail of Prionoplus reticularis elytra

Detail of Prionoplus reticularis elytra

 

Portrait of Prionoplus reticularis

Portrait of Prionoplus reticularis

 

The adult huhu beetles do not feed and live for about two weeks only. These insects spend most of their lives in the larval stage, boring into and feeding on dead wood. They can become pests in sawn timber and logs, eventually destroying the wood and leaving just the outer shell. The larvae are considered delectable wild food and were traditionally harvested by the Māori people to be eaten raw or cooked (note to self: I need to try this). At the end of their growth the larvae reach an impressive body length of 70mm and create a chamber for pupation. The adult beetle emerges from the pupa after 25 days and uses its strong mandibles to break free from the pupation chamber in the wood. The whole life cycle can take up to several years.

The adult beetles appear during the southern hemisphere spring and summer (November to March). They start their activity around dusk, and many of them reach outdoor lights and well-lit rooms in their heavy flight. I often found mating pairs in close proximity to light bulbs.

 

Many people fear these beetles for no good reason (or worse – I heard people relate to these beetles as cockroaches). The adults look a bit scary with their enormous jaws and long antennae swinging from side to side as they walk, but they are harmless and not aggressive. Well, that is, if they are not provoked. They can still use their mandibles to bite, but their bite is a lot less serious than other bites I got while in NZ (for example, ground weta’s. Stay tuned!).

 

Huhu beetle (Prionoplus reticularis). He's coming to getcha!

Huhu beetle (Prionoplus reticularis). He’s coming to getcha!