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Little Transformers: This dung beetle has had enough of this bullshit

One of the things I have been focused on in the past two years, which is partially responsible for the long silence on this blog, is sorting through the backlog of photos in my archive. This is possibly the biggest curse of digital photography; you end up with hundreds of photos from each trip that eventually accumulate and often remain untouched for years. I made it a mission of mine to start going over this material in 2019, and unfortunately I misjudged how long the whole process was going to take. The good news is that most of the work is behind me. What I loved about this task was discovering many forgotten photos, as well as some hidden gems. One such treasure is photographs of a small dung beetle I encountered one night in Belize in 2014. On the surface it doesn’t look very special but its appearance was strange enough for me to decide I should photograph it. I thought its curved hind limbs were a malformation, but back then I did not know what I know today.
Oh, past Gil. You were so naïve and cute. But I’m happy you took those photos.

Dung beetle (Deltochilum acropyge), frontal view. Toledo District, Belize

Dung beetle (Deltochilum acropyge), frontal view. Toledo District, Belize

This seemingly innocent dung beetle is a member of Deltochilum, a large neotropical genus that contains over a hundred species. What is special about this beetle in particular, and the reason it is included in the Little Transformers post series, is that it’s technically not a dung beetle. Or to be more accurate, it does not feed on dung or animal feces.
Not anymore.
Because enough is enough.
And if you are reading this post in 2021, while the world is still dealing with a global pandemic, social issues, and the effects of climate change, this small beetle may very well represent our collective mood.

Life is hard when you have to do this all day. Dung beetle (Canthon quadriguttatus) rolling a ball of fresh dung in the Ecuadorian Amazon

Life is hard when you have to do this all day. Dung beetle (Canthon quadriguttatus) rolling a ball of fresh dung in the Ecuadorian Amazon

Generally speaking, dung beetles are famous for feeding on animal feces, from which they obtain the nutrients they need. Some beetles feed directly on top or dig under the dung, while others compress the dung into a tight sphere to feed on later and roll it to their nesting spot away from other beetles. Despite the unappealing dietary habits, the competition for dung is fierce, and often several dung beetle species fight each other for a piece of the hot pie. You can probably imagine how such a competition can cause a selective pressure towards a dietary change in some dung beetles, together with suitable morphological adaptations. One example is dung beetles that shifted into feeding on rotting fruits, mushrooms, or even animal carcasses. Other beetles took it even further and moved to predation. The latter is not a simple shift and it is considered quite rare in the animal kingdom, as it requires some conditions to be met: the beetle must be able to consume and digest the prey, not to mention it must also be able to capture it.

In 2009, a study of the predatory habits of Deltochilum valgum was published. This species preys on millipedes in the rainforests of Peru. It was discovered in a survey by laying pitfall traps with different types of baits, some of which contained millipedes and attracted the Deltochilum valgum dung beetles. The millipedes were chosen as bait for the traps because beetles have been recorded feeding on dead millipedes or carrying live millipedes in the past.
But how does this species fulfill the conditions mentioned above? The choice of millipedes as prey may seem surprising. After all, many of them are poisonous or deploy chemical defenses, and usually predators avoid them. However, this is exactly what makes millipedes an unexploited resource for which there is much less competition compared to dung. In addition, millipedes are detritivores feeding on decomposing plants and mushrooms, and therefore have a large amount of organic material stored in their body that makes a great source of nutrients for the beetles. Accessible food source – check.
Next on the list is the actual hunting and killing of millipedes. This is made possible thanks to small structural changes that have occurred in the beetle’s head and hind tibiae. Instead of rolling dung balls, the hind legs have curved tibiae as an adaptation for catching and holding millipedes tightly against the beetle’s pygidium. This allows the beetle to drag the millipede to a spot where it can kill it. After taking over and dragging the prey, the beetle inserts its serrated head between the millipede’s front segments, decapitating its head. This action paralyzes the millipede completely so the beetle can start consuming its juicy insides, leaving behind only disintegrated parts of the prey’s exoskeleton at the end of the process. So far there is only one video record of Deltochilum valgum hunting a live millipede. I wish there were more but nevertheless, hunting strategy – check.

Dung beetle (Deltochilum acropyge), dorsal view. The curved hind tibiae are an adaptation for grasping millipedes.

Dung beetle (Deltochilum acropyge), dorsal view. The curved hind tibiae are an adaptation for grasping millipedes.

Much has changed since that publication. It is now clear that not one, but several Deltochilum species prey on millipedes, and they are grouped together taxonomically. Most of the species in the group share the curved hind leg adaptation for manipulating the live millipede prey. Similarly to Deltochilum valgum, they were sampled by pitfall traps with millipede bait as well. If I worked my way through the key correctly, the beetle I photographed in Belize should be Deltochilum acropyge in the valgum group within subgenus Aganhyboma, which is recorded from several countries in Central America. It is important to note that we do not know much about the life cycle of these beetles. As of writing this post it remains unclear what the beetle larvae feed on, but I would not be surprised if they require millipede prey for the completion of their development, whether on its own or mixed with dung.

Deltochilum is not the only genus of dung beetle that has evolved to use millipedes as a food source. Sceliages dung beetles from Africa are attracted to freshly dead millipedes and their larvae feed on balls of crushed millipedes, collected and prepared by the mother. And in South America Canthon dung beetles have been observed to feed on injured live and dead millipedes, leafcutter ant queens (watch a video of this behavior here, narrated in Portuguese), as well as other live dung beetles (as can be seen in this amazing Facebook video by João Burini, or on his Instagram post).

I should also mention that only a handful of Deltochilum dung beetles are predators, and looks can be deceiving. As an interesting anecdote, here is one species that according to our current knowledge is not a predator.

Dung beetle (Deltochilum carinatum). Shaped like a dark knight.

Dung beetle (Deltochilum carinatum). Shaped like a dark knight.

Deltochilum carinatum, in my opinion, is one of the most striking species in the genus. There is something about this beetle that reminds me of TMNT’s Shredder. The sharp angles, clear cuts, and overall structure. As if this body shape was made to either cut through or lock onto something.

Dung beetle (Deltochilum carinatum), dorsal view

Dung beetle (Deltochilum carinatum), dorsal view

Dung beetle (Deltochilum carinatum). One of the most peculiar-looking dung beetles in the Ecuadorian Amazon

Dung beetle (Deltochilum carinatum). One of the most peculiar-looking dung beetles in the Ecuadorian Amazon

But, as evidence suggests, this is just an ordinary dung beetle that feeds normally on dung. Maybe this will change one day, when we discover more about its life cycle and interactions with other species. For now we should enjoy it for what it is – a cool looking dung beetle. Not as badass as its murderous cousins though.

 

Little Transformers: Deinopis, the ogre-faced spider

Today’s Little Transformer is a little unusual. First off, it is a spider. This spider is so unique in its appearance and behavior that I am surprised it has not inspired any exaggerated depictions in popular culture. It spends most of its time hidden, posing as a harmless twig among the forest vegetation. It is so good at what it does, that unless it moves it would be very easily overlooked. However, when night falls this seemingly harmless twig transforms into a sophisticated killing machine. Meet Deinopis, the ogre-faced spider (also known as net-casting spider).

Net-casting spider (Deinopis sp.) from the Ecuadorian Amazon

Net-casting spider (Deinopis sp.) from the Ecuadorian Amazon

Net-casting spider (Deinopis spinosa) frontal view. Their eye arrangement is one of the weirdest of all spiders. Notice the lateral eyes are pointing down!

Net-casting spider (Deinopis spinosa) frontal view. Their eye arrangement is one of the weirdest of all spiders. Notice the lateral eyes are pointing down!

Ogre-faced spiders are found on every continent except Europe and Antarctica, but they occur mostly in warm regions of the southern hemisphere. Found primarily in Latin America, Africa, Madagascar, and Australia, these spiders all share the same appearance: brown color, elongated body with long forelegs, and an unmistakeable face. The small family Deinopidae contains only two genera: Deinopis, holding most of the species, and Menneus.

Net-casting spider (Deinopis spinosa) camouflaged as a twig or a dried leaf

Net-casting spider (Deinopis spinosa) camouflaged as a twig or a dried leaf

Interesting texture and patterns on the dorsal side of a net-casting spider (Deinopis spinosa). The legs are held tightly to form a typical 'X' shape at rest, making it look like the spider has only four legs.

Interesting texture and patterns on the dorsal side of a net-casting spider (Deinopis spinosa). The legs are held tightly to form a typical ‘X’ shape at rest, making it look like the spider has only four legs.

Deinopis are very unique among spiders for having superb vision, thanks to their huge median eyes.

Net-casting spider (Deinopis spinosa). Those eyes... You can now understand why they are called ogre-faced spiders.

Net-casting spider (Deinopis spinosa). Those eyes… You can now understand why they are called ogre-faced spiders.

A closer look at the median eyes of a net-casting spider (Deinopis spinosa). Staring straight into your wretched soul.

A closer look at the median eyes of a net-casting spider (Deinopis spinosa). Staring straight into your wretched soul.

The big eyes are what gave these spiders their common name, and they are so big that it is easy to miss the other six eyes on the spider’s head. I did my best trying to capture the stone-cold expression on a Deinopis spinosa face, but also check out Michael Doe’s amazing work with the Australian species D. subrufa. These median eyes are extremely sensitive to light, despite lacking any reflective tissue behind the lenses. Instead, a light sensitive membrane is formed inside the eyes every night, and then gets broken down at dawn. This allow the spiders to track subtle movements in complete darkness during their activity hours, something that is essential for their unique hunting strategy. While somewhat close to other weavers, ogre-faced spiders do not construct a fixed web to trap their prey. Instead they make a rather small hand-net, a handkerchief if you wish, that they use to catch insects passing nearby. The silk constructing the net is not sticky but extremely fuzzy and flexible, thanks to a special comb-like structure on the spider’s legs that stretches and frizzle the silk as it is coming out of the spider’s spinnerets.

Net made by a net-casting spider for catching prey

Net made by a net-casting spider for catching prey

A closer look at the net reveals the woolly silk used to make it. If you look carefully you will notice that it is coiled like a spring, allowing the silk to be stretched and expanded to completely cover the prey.

A closer look at the net reveals the woolly silk used to make it. If you look carefully you will notice that it is coiled like a spring, allowing the silk to be stretched and expanded to completely cover the prey.

The spider usually shapes the net as a square, and holds it loose over a branch or a leaf where an insect is likely to walk.

Net-casting spider (Deinopis sp.) from Colombia

Net-casting spider (Deinopis sp.) from Colombia

Once it spots a suitable prey, the spider quickly stretches the net and snatches the passing insect by hand. The net can be stretched and expanded up to five times its original size without being torn, thanks to the special attributes of the silk. It entangles anything it touches. The spider is extremely fast in its response that sometimes it succeeds in capturing passing insects in mid-flight, again – completely by hand. You have to appreciate the speed and accuracy that goes into this hunting technique.

Net-casting spider (Deinopis sp.) ready for an insect to pass on a nearby branch. These spiders usually place themselves right above a possible walkway for arthropods. Photographed in Ecuador

Net-casting spider (Deinopis sp.) ready for an insect to pass on a nearby branch. These spiders usually place themselves right above a possible walkway for arthropods. Photographed in Ecuador

Net-casting spider (Deinopis sp.) from Honduras

Net-casting spider (Deinopis sp.) from Honduras

It is relatively difficult to witness this behaviour in the field, mainly because by observing at night we add another component to the equation – light. In fact, in all my trips to Latin America I have encountered these spiders many times, but only once I was able to see the spider hunting… and totally missing the prey insect. So you can imagine my excitement when I realized I was going to work with one of the species, Deinopis spinosa, while it is on display at the Royal Ontario Museum’s “Spiders: Fear & Fascination” exhibition. For several weeks I tried to get a glimpse of it feeding but without success. One day I decided to toss a cricket close to it before leaving the exhibit area and within a spilt second the spider responded and caught it! I was in awe. I had to find a way to record it on video for people to see. I enlisted Daniel Kwan, one of my colleagues at the museum who has more videography experience, and we set out to produce a short movie. It took us many attempts to get decent footage of the hunting behaviour. Many times the prey crickets tried to hide, and occasionally the spider would respond to them but miss. Even though feeding the spider in an artificial environment means we had more control, it was really difficult. It makes me wonder how long the spider must wait in the wild until it is able to catch a meal.

Also worth mentioning is genus Menneus from the same family. These spiders are much smaller than Deinopis and they lack the large median eyes, therefore they are not true ogre-faced spiders. However, they spin a catch net and use the same strategy for hunting prey. The genus contains only a handful of species, distributed mainly in Australia, but with some representation in Africa. Some of the species are quite beautifully patterned compared to the plain-looking Deinopis, and there are even green-colored species! You can find some photos of Menneus spiders at the bottom of this page.

Something I was thinking about while writing this post – why do I never encounter small deinopids in the field? It would be really cute if they had miniature nets for catching even smaller insects. Even when I look for information online and in the literature, it only concerns medium-sized juveniles and adults. Could it be that the small ogre-faced spiders actually have a different hunting strategy than that of larger individuals?

Little Transformers: Bolitotherus cornutus – the first dinobeetle?

Little Transformers are back with another coleopteran representative. I usually use this platform to present insect adaptations from the tropics, however this time I am focusing on a local species with a wide distribution in central and eastern North America: the forked fungus beetle (Bolitotherus cornutus). It is one of the most iconic North American beetle species, and I remember that flipping through pages of insect books as a kid, there was always an image of a forked fungus beetle under the darkling beetles section. In fact, as soon as I arrived to Canada this was the first species I sought after. And as much as I hate to admit, I looked for it in all the wrong places. I thought it was associated with wood (it is, but in a more indirect way), and cracked open fallen logs in search for adults. Of course I found nothing. Eventually the first fungus beetles I found were under a huge woody bracket mushroom in a conservation area near Price Edward, Ontario. Today this makes me laugh because back then we drove so far, and a year later I found out that I can find the beetles within just a mere 5 mins bus ride from my house.

I must say I am puzzled why this beetle is shown as an example for darkling beetles in books. Family Tenebrionidae is big and diverse, but there are some common characteristics that stay uniform across different genera. Bolitotherus cornutus, however, is not exactly a “typical” darkling beetle. And even though this beetle is widespread and common, it is often hard to find. When I presented this beetle in a talk to a group of local naturalists and asked how many people have seen it in the wild, only one hand was raised, surprisingly or not it came from a mushroom expert.

A pair of forked fungus beetles (Bolitotherus cornutus), dorsal view

A pair of forked fungus beetles (Bolitotherus cornutus), dorsal view

At first glance, forked fungus beetles look like they were designed by a drunk military engineer. Like most members of tribe Bolitophagini, they are built like small tanks, and to some extent they also look like ones. A compact and rugged body, sealed to the outside thanks to the tight elytra forming a protective shell. The body surface is heavily granulated to provide further shock protection in case of falling to the ground, as well as camouflage against tree bark and dried bracket mushrooms that the beetles feed on. Male beetles have two sets of horns, each with a different function.

Male forked fungus beetle (Bolitotherus cornutus)

Male forked fungus beetle (Bolitotherus cornutus)

The curved thoracic horns are hairy and used for pushing an opponent off the surface while fighting for territory and mates. The length of these horns is variable depending on various conditions (both genetic and environmental), with two extreme male morphs: major with long arching horns, and minor with short stout horns.

Male forked fungus beetle (Bolitotherus cornutus), frontal view. The thoracic horns can be long!

Male forked fungus beetle (Bolitotherus cornutus), frontal view. The thoracic horns can be long!

The other set of horns are found on the beetle’s head. These are called cephalic horns and they are sometimes missing. Their function is very peculiar: males use them as a pitchfork to scrape, lift, and throw off minor individuals that cling tightly to females. By the way, other members of Bolitophagini have horns as well, for example genus Byrsax has impressive horns that make it look like a perfect samurai helmet!

Another frontal view of a male forked fungus beetle (Bolitotherus cornutus), showing its orange pom-poms.

Another frontal view of a male forked fungus beetle (Bolitotherus cornutus), showing its orange pom-poms.

Ok, but what does Bolitotherus cornutus have to do with Little Transformers? Sure, touch the beetle and it folds its legs tightly close to its body, creating an impenetrable structure. We have seen similar defense behavior in other beetle transformers, like the Ceratocanthinae pill scarab and the shiny leaf beetle. In addition, the fungus beetles also secrete a smelly mixture of chemicals when disturbed. But the reason I am mentioning it here as a transformer is because of its horns. You see, many phylogenetically distant species share similar morphological adaptations. Studying these cases of convergent evolution can teach us something about the processes these adaptations go through, as well as their function. To be more specific, how is this…

Portrait of a male forked fungus beetle (Bolitotherus cornutus)

Portrait of a male forked fungus beetle (Bolitotherus cornutus)

…any different from this?

Portrait of Machairoceratops cronusi. Art by Andrey Atuchin, used with permission.

Portrait of Machairoceratops cronusi. Art by Andrey Atuchin, used with permission.

This fabulous artwork by Andrey Atuchin shows Machairoceratops cronusi, a recently described member of the rhino-like dinosaurs, and a relative of the famous triceratops. Yes, Bolitotherus cornutus is basically a miniature six-legged dinosaur in disguise. Now I know what you are thinking. The beetle’s horns are hairy, and the dinosaur’s aren’t. That is probably true. The Machairoceratops dinosaur might have had hairy horns. We don’t know for sure (ask yourself why). But regardless, you have to agree that there is some uncanny resemblance between the two animals’ head structure. A set of flat horns arching over the head, another pair of spiky horns pointing upwards from the head, a granular neck shield… Of course, we don’t know how the dinosaurs used their horns, but we can speculate. Maybe observing the forked fungus beetles fighting can help us understand a behavior in an animal that no longer exists. The relationship between form and function in animal horns is a fascinating topic for discussion and hopefully I will write about it in more depth in the future. But I cannot help it, the more illustrations of Machairoceratops cronusi I look at, the more I see forked fungus beetles in them. It is almost as if someone placed an enormous beetle on top of the dinosaur’s skull.

Bracket mushrooms (Fomitopsis betulina) growing on birch. Bolitotherus cornutus beetles prefer to feed on old mushrooms (dark-colored, coated with moss and algae in the photo) rather than fresh ones.

Bracket mushrooms (Fomitopsis betulina) growing on birch. Bolitotherus cornutus beetles prefer to feed on old mushrooms (dark-colored, coated with moss and algae in the photo) rather than fresh ones.

The diet of forked fungus beetles is unique and restricted to bracket mushrooms (such as Fomitopsis, Ganoderma, Ischnoderma) growing on weak standing trees as well as fallen logs (by the way, they are not the only darkling beetles feeding on mushrooms). They prefer old, hardened bracket mushrooms.

Major male forked fungus beetles (Bolitotherus cornutus) fighting on top of a bracket mushroom. Notice that their granular body surface often attracts mites and tiny springtails.

Major male forked fungus beetles (Bolitotherus cornutus) fighting on top of a bracket mushroom. Notice that their granular body surface often attracts mites and tiny springtails.

On spring and summer nights males gather on the mushroom surface, where they engage in fighting tournaments to win territories (=food for the them and their offspring) and matings with the females waiting nearby. What is even more interesting is that while major males with impressive horns are distracted fighting and showing off their capabilities, the minor males sneak up on them and mate with some of the females.

A minor male forked fungus beetle (Bolitotherus cornutus) guarding a female after mating

A minor male forked fungus beetle (Bolitotherus cornutus) guarding a female after mating

The courtship process is long and elaborate, and includes climbing over the female and stridulating (acoustic communication). Males also tend to stay and guard the female to prevent other males from mating with her. After mating, females lay their eggs separately on the mushroom surface, and cover each egg with frass. This protects the eggs from desiccation as well as from predators and parasitoids.

Bolitotherus cornutus eggs appear as dark bumps on the surface of a bracket mushroom (there are 4 eggs in this photo)

Bolitotherus cornutus eggs appear as dark bumps on the surface of a bracket mushroom (there are 4 eggs in this photo)

Within 1-2 weeks the larvae hatch and immediately burrow into the mushroom. They are not the typical darkling wireworms, but instead look like hairy, soft-bodied grubs.

Young Bolitotherus cornutus larvae

Young Bolitotherus cornutus larvae

They spend their entire life inside their feeding substrate. The mushroom fruit body protects them from the elements, so they also use this space for pupation. Surprisingly, some larvae grow faster than others, and complete their metamorphosis before winter. This means that the beetles can overwinter inside the mushroom as larvae, pupae or fresh adults.

Male forked fungus beetle (Bolitotherus cornutus) emerging from a bracket mushroom

Male forked fungus beetle (Bolitotherus cornutus) emerging from a bracket mushroom

Male forked fungus beetle (Bolitotherus cornutus) burrowing into decomposing wood

Male forked fungus beetle (Bolitotherus cornutus) burrowing into decomposing wood

If you live in North America within the distribution range of this species I encourage you to get out there and look for these magnificent creatures. First of all, it is fun, and you might find other cool stuff while searching. And second, these beetles are really cool, and they can teach us a lot. They are also embarrassingly easy to keep, all they need is some pieces of the mushrooms they were collected on, the slightest humidity, and that’s it. They live for a few years as adults and readily breed in captivity, displaying all the behaviors mentioned above and more!

An active captive colony of forked fungus beetles (Bolitotherus cornutus)

An active captive colony of forked fungus beetles (Bolitotherus cornutus)

Adult forked fungus beetles (Bolitotherus cornutus) aggregating on the mushroom underside

A closeup on adult forked fungus beetles (Bolitotherus cornutus) aggregating on the mushroom underside

Little Transformers: Forcipomyia, the midge that turns into a balloon

It is time to introduce another Little Transformer! I know what you are thinking. Am I ever going to run out material for these blog posts? Maybe. Probably not. As long as there are arthropods around, their life history and morphological diversity guarantees that I will always find examples for interesting deceptions and transformations. Up until now I mostly focused on animals that can change form quickly, assuming the appearance of something else as a defense response against predators and to avoid detection. The case presented in this post is a little different because it does not follow a quick change of form, but rather a slow one, over the course of a life stage. I should be cautious here, because under this definition every insect that goes through complete metamorphosis from larva to adult can be considered a Little Transformer (butterflies, beetles etc’). Even amphibians fall under this loose definition. And to some extent they ARE transformers, because the changes they go through during development are extreme. But this is not the topic for this series of posts. When I talk about a big change happening within a life stage, I mean that the animal starts as one thing, and by the end of the stage its appearance and function has changed into something else completely. And no example is better to show this than the parasitic midges of the genus Forcipomyia.

Biting midge (Forcipomyia sp.) feeding on the hemolymph of a moth caterpillar. Photographed in Belize

Biting midge (Forcipomyia sp.) feeding on the hemolymph of a moth caterpillar. Photographed in Belize

Here is the Forcipomyia midge with the whole caterpillar to give a better sense of scale

Here is the Forcipomyia midge with the whole caterpillar to give a better sense of scale

Forcipomyia is a large genus in the midge family Ceratopogonidae, with a worldwide distribution and diverse habitat preferences. There are now over 1,000 described species of Forcipomyia. The adults of some species are known as important pollinators of cacao and other plants of economic importance in tropical and subtropical areas. However, many species in the genus are blood-feeders, somewhat characteristic to ceratopogonids as the common name to the family suggests (biting midges). These parasites have interesting relationships with different insect hosts, and they can be found feeding on the hemolymph (insect blood) of grasshoppers, katydids, stick insects, butterflies, true bugs, and even skittish dragonflies. In fact, these interactions are so fascinating and overlooked, that only after spending some time in the field one can notice the midges have a preference for certain host species to feed from.

Sometimes the biting midges sneak into the photo without me noticing. I photographed these mating grasshoppers (Cloephoracris festae), but they have an accompanying Forcipomyia. Can you spot it?

Sometimes the biting midges sneak into the photo without me noticing. I photographed these mating grasshoppers (Cloephoracris festae), but they have an accompanying Forcipomyia. Can you spot it?

But let’s go back to the transformation they go through, because in one group of species, subgenus Microhelea, it is truly remarkable. The female Forcipomyia midge begins her adult stage with an active lifestyle. She flies about in the forest, feeding on nectar from small flowers. As days go by, she starts craving for blood and search for insects to bite. When she locates her preferred host, using her serrated mouthparts she proceeds to bite it in an area that has soft tissue: antennae, legs joints, wing veins, or between body segments. Once she found the right spot that will fulfill her dietary needs, the female midge attaches to it firmly, and… doesn’t let go, thanks to specialized claws on her feet. She sucks and gulps the insect’s blood, filtering the nutrients and secreting the excess fluids as clear droplets.

Tick fly (Forcipomyia sp.) feeding on the hemolymph of a walking stick

Tick fly (Forcipomyia sp.) feeding on the hemolymph of a walking stick

The midge stays attached like this for quite a while, and soon this sessile lifestyle starts taking its toll on the small parasite. She starts to put on weight. Then, she usually losses her wings – she will not need them anymore because the added mass from the developing eggs prevents her from taking off.

Female Forcipomyia swelling while feeding. She lost her wings but can still use her legs to hold firmly onto the host

Female Forcipomyia swelling while feeding. She lost her wings but can still use her legs to hold firmly onto the host

Forcipomyia getting fatter... but not quite there yet

Forcipomyia getting fatter… but not quite there yet

As she continues to swell like a grapefruit, the Forcipomyia midge also losses the ability to use her legs. She does not need to leave anyway, but she is so bloated that she cannot even hold onto the body of the host, and the only thing keeping the two connected are the midge’s mouthparts.

Female tick fly (Forcipomyia sp.) at the final stage of feeding. Her legs released their grip on the host and at this point the midge has fully transformed into a passive parasite that looks like a balloon.

Female tick fly (Forcipomyia sp.) at the final stage of feeding. Her legs released their grip on the host and at this point the midge has fully transformed into a passive parasite that looks like a balloon.

Stick insect (Pseudophasma bispinosum) carrying tick flies (Forcipomyia sp.) at different stages of feeding. Photographed in Ecuador

Stick insect (Pseudophasma bispinosum) carrying tick flies (Forcipomyia sp.) at different stages of feeding. Photographed in Ecuador

At this point, the engorged biting midge is no different than a tick, and indeed many refer to these parasitic Forcipomyia as tick-flies. Sometimes I like to imagine these fat dipterans disconnecting from their host and floating upwards like a balloon filled with helium, reaching above the forest canopy and flying into space. In reality, the exact opposite happens. The Forcipomyia female eventually leaves the host and drops to the ground, where she lays her eggs and finishes her role. And the male Forcipomyia? They are mostly unknown. Because males are never found feeding on insect hosts, it is safe to assume that they do not feed on blood, and prefer to keep a vegan diet of sweet nectar.

An engorged female tick fly (Forcipomyia sp.) after dropping from its host

An engorged female tick fly (Forcipomyia sp.) after dropping from its host

What about the larvae, are they parasites too? The majority of the research on biting midges has focused on the adults, due to their economic and medical significance, as well as their important role in aquatic ecosystems. Larvae of most ceratopogonids are unknown because finding them in their natural habitats can be challenging. They usually inhabit aquatic and semiaquatic habitats, but in the case of Forcipomyia the larvae are terrestrial and prefer to feed on moist detritus and organic matter under bark or in moss. In some species they feed on algae.

This stick insect is staring at me with tired eyes. I wonder if it is aware of the two hitchhikers it is carrying?

This stick insect is staring at me with tired eyes. I wonder if it is aware of the two hitchhikers it is carrying?

With so many aspects of their life history still unknown, and especially due to their ecological and economical importance, you would expect to see more active research on Forcipomyia. The bad news is that there is not enough research going on. A few years ago, I approached Dr. Stephen Marshall, a dipterologist from University of Guelph, and suggested doing a PhD study about Forcipomyia’s biology, phylogenetics, and their relationships with their hosts. I was politely refused, unfortunately. I still believe there is potential for a cool project involving Forcipomyia, maybe someone will pursue it in the future.

Little Transformers: Lamprosoma, the living Christmas ornament

Ah, the joy of transforming beetles. The first Little Transformer that opened this series of posts was a beetle – a Ceratocanthinae pill scarab that transforms into a perfect sphere and drops off to escape predators. It is an impressive evolutionary achievement that merges a successful body design and anti-predator behavior. I should mention though that many beetle species from other families use this strategy to avoid predation, some more successfully than others. One such example is a genus of small beetles from the leaf beetle family (Chrysomelidae): Lamprosoma.

Shiny leaf beetle (Lamprosoma sp.) from the Ecuadorian Amazon

Shiny leaf beetle (Lamprosoma sp.) from the Ecuadorian Amazon

When I first encountered a Lamprosoma beetle I thought it was a piece of plastic that someone discarded in the rainforest. There is something almost artificial about their appearance, shiny metallic colors combined with a compact shape. Not all species are colorful, by the way. The genus contains about 130 species, all with a neotropical distribution, some of which are completely black in color. With a body length of less than 1cm they are easy to miss in the dense vegetation of the tropical forest. Nevertheless, over the years I have encountered them more and more frequently. Unfortunately for me, identifying these beetles to the species level requires an expertise that I do not have, because there are many similar-looking species, and possibly also new species that have not been described yet.

Shiny leaf beetle (Lamprosoma sp.) from Honduras

Shiny leaf beetle (Lamprosoma sp.) from Honduras

The beetles are dome-shaped, and have very short legs. I think “cute” is the best way to describe them. As mentioned above, Lamprosoma can transform into a ball when threatened. In contrast to Ceratocanthinae beetles that have dedicated grooves to hold the legs and head in place, members of genus Lamprosoma have no such features. The beetle tucks in its head and holds its legs tightly close to its body, making it a neat impenetrable package.

Shiny leaf beetle (Lamprosoma sp.), a ventral view showing how neatly they press their legs against the body when forming the ball

Shiny leaf beetle (Lamprosoma sp.), a ventral view showing how neatly they press their legs against the body when forming the ball

Shiny leaf beetle (Lamprosoma sp.) in ball-mode. Mimicking a Christmas ornament.

Shiny leaf beetle (Lamprosoma sp.) in ball-mode. Mimicking a Christmas ornament.

In species with shiny metallic colors it is hard not to see the resemblance to the glass balls used as Christmas ornaments (maybe an idea for a future product?). Once the danger is out of sight, the beetle loosens its legs and walks away.

Shiny leaf beetle (Lamprosoma sp.) transformation sequence from ball-mode to beetle-mode. How can you not fall in love with those stubby feet?

Shiny leaf beetle (Lamprosoma sp.) transformation sequence from ball-mode to beetle-mode. How can you not fall in love with those stubby feet?

Lamprosoma are phytophagous beetles, meaning that they feed on plants. Both adults and larvae feed on leaves, and can be potential pests due to damage they can cause to foliage. The species shown here seem to be associated with cacao trees, and were found under leaves during the day. While the adults are very showy, the larvae are cryptic to avoid predators: they construct a case from frass and wood debris, and carry it around throughout their lifetime. The case is often shaped like a bent thorn, and blends perfectly with the branches the larvae live on. When threatened the larva retreat into the case and hold it firmly against the branch, preventing predators (such as ants and wasps) from accessing inside.

Another example of Lamprosoma sp. in ball-mode

Another example of Lamprosoma sp. in ball-mode

Shiny leaf beetle (Lamprosoma sp.). Full beetle-mode!

Shiny leaf beetle (Lamprosoma sp.). Full beetle-mode!

Little Transformers: Myrmarachne formicaria

Little Transformers is back! And this time our star is a small jumping spider that goes out of its way to masquerade as an ant.

I am often accused for not writing about topics related to Canada on this blog. While this is not entirely true, I could have without doubt posted more about local critters. It is a great time to do so now, as I will be taking the opportunity to address several events.
Firstly, it is now October, and we are getting closer and closer to Halloween (Oct 31st). Nine years ago, the Arachtober initiative was born: why wait till the end of the month to celebrate spiders? Let’s celebrate them and other arachnids throughout the entire month of October! And so, during the month of October we give arachnids more exposure in hopes to educate the general public about these magnificent and important creatures.
Secondly, a new initiative is slowly forming, International Jumping Spider Day, on October 10th. The idea is to use the easily adored jumping spiders as the gateway arachnid for changing the often-negative public perception of spiders. I wholeheartedly support this idea and hope to see it catching on.
Lastly, a shameless plug: You may have noticed that this blog is nominated for the 2017 People’s Choice Awards: Canada’s Favourite Science Online. It is a huge honor to be included with other excellent science blogs and sites on the same list. If you like the content and stories that I post, you can show your appreciation by voting following this link. I wish to thank those who already voted in support of this blog. While this nomination has nothing to do with spiders, I thought it is a great opportunity to write a blog post about an arthropod found in Canada.

Female ant-mimicking jumping spider (Myrmarachne formicaria) wants your attention

Female ant-mimicking jumping spider (Myrmarachne formicaria) wants your attention

After this short introduction, it is time to present our first local Little Transformer, the ant-mimicking jumping spider Myrmarachne formicaria. It is one of the nicest looking spiders here in Ontario, and it is surprisingly abundant in its habitat. Alas, there is a small catch here. While this jumping spider is local, it is not native to Canada. This species was first detected in North America in 2001, and later established in Tommy Thompson Park in Toronto in 2015. It originates in the Palearctic region, more specifically Europe and Asia. Despite this, these spiders feel right at home in Toronto, as it seems that they are spreading away from the park containing the main population. This year, Sean McCann recorded Myrmarachne in Scarborough (east Toronto), and I found them in Mississauga (west of Toronto).

Female ant-mimicking jumping spider (Myrmarachne formicaria) masquerading as an ant

Female ant-mimicking jumping spider (Myrmarachne formicaria) masquerading as an ant

Myrmarachne formicaria is an elongated jumping spider that takes the appearance of a small ant, and here in Ontario it is associated with the European fire ant, Myrmica rubra, also an introduced species. Isn’t it interesting how these two non-native species managed to find each other on unfamiliar land? The spider has long and slender legs just like those of an ant, and the banded forelegs are slightly thicker to resemble antennae. The cephalothorax has a depression to echo the segmentation in ants separating head from thorax. The abdomen is long with a narrow connection to the cephalothorax, reminiscent of an ant’s petiole. Surprisingly, in this species the pedipalps (normally a distinguishing character between males and females) are swollen in females, a trait usually seen only in males. Males on the other hand have enormous toothed chelicerae that stick right out of their faces. I suspected this is a sexually selected trait used in fights for females, and this was later confirmed by Sean McCann (check out his amazing shots here).

Female ant-mimicking jumping spiders (Myrmarachne formicaria) have swollen pedipalps

Female ant-mimicking jumping spiders (Myrmarachne formicaria) have swollen pedipalps

Male duck-mimicking jumping spide... um, excuse me ANT-mimicking jumping spider. Quack quack.

Male duck-mimicking jumping spide… um, excuse me ANT-mimicking jumping spider. Quack quack.

This begs the question, why do Myrmarachne spiders look like ants? Do the spiders use their appearance to fool the ants into thinking they are members of their own colony in order to sneak up on them and prey on ant workers or larvae? Not really. For starters, the ant species approached by Myrmarachne formicaria are usually not visual creatures. They rely more on their chemical communication, using volatile pheromones, for navigation and recognition. Moreover, the spiders seem to deliberately avoid any contact with the ant workers. They may walk among the ants, but they always keep their distance from them. In fact, when I experimented and isolated a few spiders within a group of ants, the spiders chose to stay still, and only when the path was clear they made a run for it. I also noticed that the ants display an aggressive response when encountering a spider. So the ants are not the target of this mimicry. Who is? Us. Or more precisely, predators. You see, the spider not only looks like an ant and spend its time close to the ants, it also moves like an ant.

Myrmarachne formicaria always keep a safe distance from Myrmica rubra workers

Myrmarachne formicaria always keep a safe distance from Myrmica rubra workers

A recent study looked into the locomotion of Myrmarachne formicaria jumping spiders and found that they do not move like their peers. First of all, instead of jumping like most salticid spiders, they move forward in a series of short sprints. But they also move in a pattern that resembles the movement of ants following a pheromone trail, back and forth in a winding wave motion, instead of random strolling and stopping often we see in other spiders. If it looks like an ant and moves like an ant… it might be good enough to fool predators that it is an ant. And I can attest to this – it is extremely difficult to keep track of a Myrmarachne spider moving about in an area with ant activity. Look away, and you will need all the luck in the world to find it again. The spiders also benefit from being close to a colony of highly defensive ants. Myrmica rubra is easily alarmed and has its reputation when it comes to stinging intruders.

Some Myrmarachne formicaria feature a two-colored cephalothorax, to emphasize the part that mimics the ant's head

Some Myrmarachne formicaria feature a two-colored cephalothorax, to emphasize the part that mimics the ant’s head

If they do not hunt the ants, what do these spiders feed on? They seem to go after soft-bodied insects, and they are especially fond of dipterans: small flies, mosquitoes, midges etc’.

Male ant-mimicking jumping spider (Myrmarachne formicaria) feeding on a chironomid midge

Male ant-mimicking jumping spider (Myrmarachne formicaria) feeding on a chironomid midge

A closer look at the feeding Myrmarachne male reveals the weaponized chelicerae, used in fighting other males

A closer look at the feeding Myrmarachne male reveals the weaponized chelicerae, used in fighting other males

At this point you might ask yourself why I included this jumping spider in my Little Transformers series. Sure, it mimics an ant, but that’s it. Or is it? In order to qualify as a Little Transformer the arthropod needs to change something in its appearance to transform into something different. So far we have seen that these spiders move in an atypical fashion to jumping spiders. But there is one more thing they do to conceal their salticid identity. What is the one, fail-safe characteristic of jumping spiders? Those huge front eyes! If only the spider could hide them, it would look like the perfect ant. And they do exactly that.

I look at this spider and I see an ant staring back at me.

I look at this spider and I see an ant staring back at me.

Myrmarachne often wave their forelegs in the air to mimic the ants’ antennae, but the legs also hide their most recognizable feature, the bulging front eyes. Females seem to do a better job at this than males, transforming into ants right before our eyes.

Male ant-mimicking jumping spider (Myrmarachne formicaria). Even on a side-view I still see a weird duck...

Male ant-mimicking jumping spider (Myrmarachne formicaria). Even on a side-view I still see a weird duck…

What is most intriguing here is that the rear pair of eyes evolved to be very large, bearing a striking resemblance in their size and position to ant eyes.

Ant-mimicry is quite common among arthropds, and many species of jumping spiders deploy this strategy as an anti-predator defense or to assist in foraging. While some do not consider Myrmarachne formicaria as a case of perfect mimicry, it is a gorgeous spider with intriguing behavior. Besides, mimicry does not have to be perfect to satisfy our aesthetic desires. It only has to be good enough to benefit the spider’s survival.

Little Transformers: Dysodius

When I first came up with the idea of Little Transformers, what I had in mind were insects that can masquerade as other objects by changing their appearance or behavior. I consider myself a “mild” Transformers fan: I like the concept of entities taking the form of other things, very much like how mimicry or camouflage work in nature. I have said before that I am not a fan of the current iteration of Transformers, those movies are so bad. However, I am going to take advantage of the upcoming release of the new Transformers movie (and I cannot believe I am using this as my reasoning) to post about yet another Little Transformer. This one does not really transform though, but it sure looks like one of the robots in those films. While I am not sure who is behind the designs for the robots, it was clear right from the start that there is some insectoid perspective to their appearance. I have always preferred the simple “blocky” design of the original cartoon show, but I can see how that would not look very realistic.

As mentioned above, our Little Transformer may not pass as the best example for a mode-changer, but it has an alien-like appearance. Meet Dysodius, a bark bug that belongs to the family of flatbugs, Aradidae.

Bark bug (Dysodius lunatus) crawling on a fallen log. Amazon Basin, Ecuador

Bark bug (Dysodius lunatus) crawling on a fallen log. Amazon Basin, Ecuador

Aradidae are cryptic insects, spending most of their time hidden on or under bark, and inside fallen logs. They feed on fungi: at nighttime both adults and nymphs can be seen aggregating near fruit bodies of mushrooms, sticking their proboscis into the soft flesh. It is a fungi cocktail party, and everyone is invited! Some species of Aradidae even display parental care and protect their offspring. Aradids are incredibly flat, a character that helps them to squeeze into tight crevices and take advantage of the complex habitat that is the bark’s surface, in order to remain hidden from the ever-searching eyes of predators.

Lateral view of a bark bug (Dysodius lunatus). So flat it could sit comfortably inside a paper envelope.

Lateral view of a bark bug (Dysodius lunatus). So flat it could sit comfortably inside a paper envelope.

Members of genus Dysodius are particularly interesting because of the their unique body structure, featuring curved lobes protruding from the pronotum and a crown of “fins” surrounding their abdominal segments. They also have tiny wings, so tiny that it makes me wonder if these wings are truly functional and can create enough force to lift the insect off the ground.

Bark bug (Dysodius lunatus), dorsal view

Bark bug (Dysodius lunatus), dorsal view

Dysodius are also very slow animals. They usually rely on their excellent camouflage rather than speed to avoid threats.

Bark bug (Dysodius lunatus) camouflaged on a fallen log

Bark bug (Dysodius lunatus) camouflaged on a fallen log

Their body surface is rough and often mottled with moss-like splotches. It is also wettable just like tree bark, in other words the colors get darker when getting wet by rain (unlike the water-repellent integument of other bugs), ensuring that the insect is still camouflaged even in rainy conditions.

Bark bugs (Dysodius spp.) from Belize (left) and Ecuador (right) demonstrating different coloration and textures of the body surface.

Bark bugs (Dysodius spp.) from Belize (left) and Ecuador (right) demonstrating different coloration and textures of the body surface.

This begs the question why am I including Dysodius in the Little Transformers series? After all, these insects are already “transformed” and do not change their appearance any further. They already look like a piece of bark. To understand why they are mentioned within these posts, you need to view them from the underside.

Bark bug (Dysodius lunatus), facial view. Am I the only one seeing a robot here?

Bark bug (Dysodius lunatus), facial view. Am I the only one seeing a robot here?

Aradidae, and Dysodius in particular, have one of the most robotic faces in the entire insect world, a face that could easily fit in the current Transformers movie franchise.
If you are not convinced yet, here is a closer look.

Portrait of a bark bug (Dysodius lunatus)

Portrait of a bark bug (Dysodius lunatus)

So if you think the Transformers movies are cool, insects do it better and have been doing it for far longer time. How does that quote from the trailer go?

“A thousand years we’ve kept it hidden. The secret history of Transformers…”

It was hidden all right. But not anymore. I am slowly unearthing this secret, exposing the existence of Transformers right here under our nose. You’re welcome.

Little Transformers: Pycnopalpa bicordata

It comes as no surprise that the first two “Little Transformers” presented on this blog were beetles. Many beetles are capable of folding, taking the shape of different structures, whether it is for camouflage or as a means of defense against predators. I will surely present more examples of transforming beetles in future posts. However, there are other insects out there that have the same transformation ability. I had the fortune of meeting one of those insects while staying at a jungle lodge in Honduras. My visit was in the middle of a dry spell and insects were surprisingly scarce. Many of the hikes I took in the rainforest were unfruitful. In my frustration I decided to check the screen windows outside a nearby facility because sometimes insects decide to rest on the mesh. I did spot a few nice finds, and then, I saw this.

"It's a bird! It's a plane!"

“It’s a bird! It’s a plane!”

My first thought was ‘that is one weird-looking moth’.
Let me explain.
My entomologist mind is on a constant search to find familiar patterns in objects that I see, because in the tropics deception is lurking everywhere. What I saw first was the animal’s shape and took it immediately for a winged insect. Then the coloration and the pose reminded me of some Erebidae moths (for example, genus Eutelia).
It took me a couple of short attempts to refocus my eyes on what is important before I could see that this is not a moth at all.

Now that the insect is off the net, we can take a better look. Dorsal view.

Now that the insect is off the net, we can take a better look. Dorsal view.

Another view of this amazing insect

Another view of this amazing insect

This is in fact a katydid nymph, Pycnopalpa bicordata, and it is so good at what it does that I was not able to locate it much later as it was sitting among fallen leaves in the vial I put it into. Whenever it is inactive it will assume this position, blending in with tree bark or leaf litter in the forest understory. Whether it resembles a moth or not is a matter of personal opinion at this point, because unless there is concrete evidence for an unpalatable moth model that this katydid is mimicking, the body posture this katydid takes can be within a different context altogether, such as a shredded fallen leaf or something similar.

Viewing from the side reveals that this is a leaf-mimicking katydid nymph (Pycnopalpa bicordata) at rest

Viewing from the side reveals that this is a leaf-mimicking katydid nymph (Pycnopalpa bicordata) at rest

The nymph (Pycnopalpa bicordata) in full katydid-mode

The nymph (Pycnopalpa bicordata) in full katydid-mode

Leaf-mimicking katydid nymph (Pycnopalpa bicordata). Clever girl!

Leaf-mimicking katydid nymph (Pycnopalpa bicordata). Clever girl!

As mentioned above, this is a nymph. A juvenile female to be more accurate, as can be seen by her sickle-shaped ovipositor. So what does the adult katydid look like? I was expecting some mind-blowing leaf appearance; maybe with flattened fins and spines on the legs, to mimic a dried leaf chewed up to its veins. You can safely say that I was exaggerating, and in the end when the nymph molted to its adult stage I was rather disappointed.

The adult Pycnopalpa bicordata is a delicate leaf-mimicking katydid. This one is a male.

The adult Pycnopalpa bicordata is a delicate leaf-mimicking katydid. This one is a male.

The adult Pycnopalpa bicordata is a very delicate insect with no major body modifications for mimicry or camouflage. Yes, it still looks very much like a leaf – having vivid green wings with transparent cells surrounded with brown margins, representing consumed parts or sunburn damage to leaf tissue. But the adult stage pales in comparison to the ingenious structural design of the nymph. Still, it is very nice to find Little Transformers outside the realm of Coleoptera. Moreover, among the orthopterans, I can think of at least one additional species of katydid and several grasshoppers that fall under my definition for Little Transformers. Hopefully we will get to learn about them in future posts.

Little Transformers: Eburia pedestris

We are back to celebrate little transformers: insects that are more than meets the eye. In this post I feature an insect whose transformation may seem a little awkward at first. It is not of cryptic nature, and it is not a case of mimicry.

While doing research about whip spiders in Belize, I also surveyed the insect biodiversity of one site, and so made sure to visit the light traps that we set up in several spots. The traps attracted an impressive diversity of insects, including moths, leafhoppers, ants, mantids, and katydids. One night a beautiful longhorn beetle (family Cerambycidae) showed up at the light trap. I did not recognize it at first so I collected it for a short Meet Your Neighbours session.

Longhorn beetle (Eburia pedestris) from Belize

Longhorn beetle (Eburia pedestris) from Belize

It was Eburia pedestris, a member in a genus of hardwood-boring longhorn beetles with a wide distribution in the Americas. I took a few decent shots. The beetle was trying to escape of course, so I reached out to grab it before it fell from the acrylic sheet. The moment I touched it something interesting happened. It crossed its legs and took a sitting position. I could not help it and I sneaked a loud laugh, because it looked like the beetle was in the middle of a yoga practice. It stayed in this comical position for a while, so I took some additional shots.

Longhorn beetle (Eburia pedestris) just sitting around

Longhorn beetle (Eburia pedestris) just sitting around

Another view of the strange pose taken by Eburia pedestris

Another view of the strange pose taken by Eburia pedestris

The strange position did not make a lot of sense to me, but I thought maybe it was a more elaborate way of playing dead, a common behavior in many beetle families (which will probably be featured more than once in this series). I finally decided not to wait for the cerambycid to “open up” so I grabbed it in my hand to put it back into the vial before releasing it outside. And then it hit me.

I mean, it literally hit me.
I felt my hand being pierced in several spots. Blood was dripping from my fingers.
You see, there is a reason why Eburia beetles take this unusual body posture. Look at the beetle’s leg joints and at the tips of the elytra. By taking a “sitting” pose, the beetle transforms into a prickly business, pointing sharp spikes in all directions, making it difficult for large predators like myself to handle the beetle. It will also not hesitate to use its other cold weapon: biting mandibles. Something I only noticed much later when I examined the photos – notice how the beetle contracts its abdomen, to make the elytral spines more prominent. Even with caution it was difficult not to get your skin punctured by the spines. They are as sharp as syringes. I would not want to imagine the experience for a mammal trying to eat this beetle. Ouch.

Longhorn beetle (Eburia pedestris) in defense posture. Grab it if you can.

Longhorn beetle (Eburia pedestris) in defense posture. Grab it if you can.

Some insects prove to us that avoiding predators is not all about hiding, mimicking other organisms, and advertising toxicity or potent venom. There are other, more creative ways to survive in the jungle out there. I will even take it a step further and say this Eburia beetle is comparable to the armadillo girdled lizard in its behavior. Nature is so awesome.

Little Transformers: Ceratocanthinae beetles

If you missed my subliminal message in the last two sentences of the previous post, I am not done yet with the Transformers. I was building up to this exact moment. You see, insecticons ARE everywhere. Maybe not in the same context as depicted on the TV series, but still there are creatures out there that are more than meets the eye. A substantial part of their existence relies on fooling predators into thinking they are something else: an inanimate object, another animal, or something completely different. I am happy to introduce “Little Transformers”, a new section on the blog, in which I will present interesting cases of insects in disguise.

We are launching this series with the beetle that started it all – the pill scarab (member of subfamily Ceratocanthinae). If you run an internet search with the words “transformer” and “insect”, there is a high chance that one of the results will be an image created by Kenji Nishida, showing a small beetle from Costa Rica transforming from a ball-mode to beetle-mode. The image has gone viral soon after being posted online, and now that Ceratocanthus beetle is fairly recognized by title as the beetle transformer. I have posted an image of a similar beetle before on this blog, a Ceratocanthus species I found in Belize. It was featured in an excellent phylogenetic paper about this subfamily by Alberto Ballerio and Vasily Grebennikov, and even made it to the journal’s cover. I recommend checking the paper out, even if you are not interested in these beetles, you can enjoy the beautiful images showing the impressive diversity of the group.

Pill scarab beetle (Ceratocanthus sp.) from Belize, showing the spherical alternative mode typical to members of Ceratocanthinae

Pill scarab beetle (Ceratocanthus sp.) from Belize, showing the spherical alternative mode typical to members of Ceratocanthinae

Ceratocanthinae are a subfamily of Hybosoridae within the Scarabaeoidea beetle group, containing over 360 described species, most of which are small in size (just a few millimeters in length). They have a wide distribution range mainly in tropical regions throughout the world, with only a few genera and species recorded close to temperate regions. Ceratocanthinae also occupy different types of habitats. The highest diversity seems to be in new world rainforests, but they also occur in temperate forests, subtropical forests, savannahs, and even in coastal deserts. Adult Ceratocanthinae are best known for their ability to conglobate: rolling into a nearly perfect ball. The elytra, pronotum, head, and all six tibiae interlock with each other by means of grooves and corresponding ridges, forming a tightly connected external surface. Many beetles take the form of a tight compact structure when threatened, however in Ceratocanthinae the tibiae of all six legs participate in forming the external hard surface of the sphere, unlike in other beetles.

Ceratocanthus sp. transformation sequence from ball-mode to beetle-mode

Ceratocanthus sp. transformation sequence from ball-mode to beetle-mode

It is fascinating to observe these beetles transform to and from their alternative mode. Nancy Miorelli, an entomologist and science communicator living in the Maquipucuna reserve in Ecuador, recently recorded a video showing the beetle opening up (by the way, Nancy also creates beautiful jewelry from insect wings and Tagua nut with the proceedings supporting rainforest conservation and the local community. You can check out her shop here).

Why do they do this? The ability to roll into a tight compact structure probably has anti-predatory and physiological advantages, such as moisture retention or thermoregulation. It seems that the primary use is as a form of crypsis, to avoid detection by nearby predators, however after following several beetles in the wild I noticed that they stay transformed into the ball-mode even when they are not active; perhaps it is a way for them to rest too.

Pill scarab beetle (Ceratocanthus sp.) from southern Belize. Full beetle-mode!

Pill scarab beetle (Ceratocanthus sp.) from southern Belize. Full beetle-mode!

Unfortunately, very little is known about the biology of Ceratocanthinae. They are sometimes found under bark, in tree holes, and in decomposing wood. Several records report adults and larvae that have been found in termite nests. However, It is unclear whether Ceratocanthinae are termitophilous and have a relationship with the termite hosts. The ability to roll into a ball can serve as a defense and might be an adaptation for living in the hostile environment of a termite nest. Another suggestion defines the beetles as termitariophilous, in other words attracted to the properties of the termite nest itself as opposed to its inhabitants. While the feeding habits of Ceratocanthinae are mostly unknown, a handful of observations report adults feeding on various fungi. It is therefore possible that Ceratocanthinae are attracted to some of the fungi growing on the surface of termite nests. This can explain the presence of the beetles in the nests, but unfortunately without additional data about the beetles’ life history it would be difficult to validate this connection.

So the next time you are out in the field and you stumble upon a tiny sphere in a peculiar place, take a closer look. If it looks like a beetle mummy, then bingo! You have a Little Transformer. Now all you need to do is wait for it to open up… Patience. Lots of patience.