Archive For: Insects

The Plot Thickens: This caterpillar ain’t big enough for the two of us

Some of my favorite insects to find while out in the field are hawkmoth caterpillars, or hornworms (named after the characteristic “tail”). They are big, squishy sausages that often show off dazzling colors, sometimes with interesting anti-predator adaptations like eyespots and mimicry. All these characters make the hawkmoth caterpillar look like a toy just waiting for you to play with. The sad truth is that being big and flashy in the natural world often comes with a price. There is danger lurking in every corner. Despite the bright colors and adaptations, birds and lizards do not hesitate to snatch the caterpillars from branches, pathogens and spores of entomophagous fungi scattered everywhere increase the chance for passive infections, and parasitoids are always on the lookout for chunky hosts for their offspring. And the reality is that many of the caterpillars we get to encounter outdoors are already infected with something. I learned this the hard way: as a kid I used to rear a lot of butterflies and moths collected as caterpillars in the field, and many times I was devastated to witness my cute pets being reduced into a sticky mess while wiggly worm-like creatures emerge from their bodies. Sometimes I wonder how lepidopterans manage to keep their populations stable with so many enemies around.

On one of my visits to the beautiful town of Mindo Ecuador, I came across a young hornworm. Despite finding it at daytime, the caterpillar remained calm (many hornworms do their best to disappear from plain sight during the day) so I decided to photograph it.

A cute hawkmoth caterpillar. See that black spot on the leaf? It is important to our story.

A cute hawkmoth caterpillar. See that black spot on the leaf? It is important to our story.

After taking a few shots I noticed a black splotch in the photo that I didn’t like, so I decided to change the angle of view. Little did I know this was a wasp that just arrived at the leaf to check out the caterpillar. A few photos later its identity became clear: It was a species of Brachymeria, a tiny wasp that belongs to the large parasitoid family Chalcididae.

The hawkmoth caterpillar being visited by a parasitoid chalcidid wasp (Brachymeria sp.)

The hawkmoth caterpillar being visited by a parasitoid chalcidid wasp (Brachymeria sp.)

Chalcidid wasps can be easily recognized by their modified hindlegs that resemble mantids’ raptorial forelegs. The function of these structures is largely unclear. The adult wasps feed on nectar and other liquid foods, and do not use the legs for catching prey. There is a paper describing an interesting behavior in which the females use their legs in fighting over a host’s egg mass. Even more interesting are the last three paragraphs of the paper, with additional examples and hypotheses. It seems like there is no single function for these modified hindlegs and it really depends on the species and its biology. One example really stands out: “The female of Lasiochalcida igiliensis literally jumps into the jaws of antlions and holds the mandibles agape with her hind legs while ovipositing.”

Going back to our little Brachymeria and the hawkmoth caterpillar, at first the wasp just strolled peacefully on the leaf next to the caterpillar, but within a few minutes it hopped, quite literally, on the caterpillar and started walking on it, exploring its body surface while frantically moving its antennae.

The wasp jumped on the caterpillar's proleg and started crawling on its body

The wasp jumped on the caterpillar’s proleg and started crawling on its body

In general, the caterpillar doesn’t enjoy this attention, and often swiftly moves its head backwards in an attempt to drive the parasitoid away. It usually does not work. Once a caterpillar has been spotted and marked by a parasitoid as a host, it will be attacked (here’s a fantastic video showing this behavior, notice that the fly sitting nearby is another parasitoid of hornworms – a tachinid fly!).

A closeup of the parasitoid chalcidid wasp (Brachymeria sp.) as it was walking on the hawkmoth caterpillar

A closeup of the parasitoid chalcidid wasp (Brachymeria sp.) as it was walking on the hawkmoth caterpillar

As I was taking photos of the tiny wasp antennating the caterpillar, from the corner of my eye I noticed a bright yellow object flashing in. A second wasp, a golden Conura species, swooshed into the scene and started harassing the busy Brachymeria wasp.

While the Brachymeria was busy exploring the caterpillar, another wasp (Conura sp.) rushed in to fight for it

While the Brachymeria was busy exploring the caterpillar, another wasp (Conura sp.) rushed in to fight for it

For a short while, the Conura striked from above repeatedly, yet the Brachymeria stood her ground. Eventually the Conura got fed up and attempted to grab onto the other wasp and pull her away from the host. After several tries she succeeded, and the two started swirling in the air, before the Brachymeria returned to her business on top of the caterpillar. The golden wasp did not give up and returned for a second attack and then a third.

The two chalcidid wasps (Brachymeria sp. and Conura sp.) fighting over the host. This was taken moments before the Conura grabbed the other wasp's head and dislodged it from the caterpillar.

The two chalcidid wasps (Brachymeria sp. and Conura sp.) fighting over the host. This was taken moments before the Conura grabbed the other wasp’s head and dislodged it from the caterpillar.

This was very exciting to watch, but to be honest I was waiting eagerly to see if the wasps would use their modified hindlegs during the fight. Unfortunately, I was not able to detect any special maneuvers that involved grabbing with those legs.

Why did this happen? There are several possible explanations. The simplest one is that there is a shortage of caterpillar hosts and the two wasps are competing for the same source of food for their larvae. However, an alternative explanation suggests that the caterpillar has already been infected with a parasitoid before the first wasp found it. Many chalcidid wasps are hyperparasitoids – they do not feed on the big hosts (the caterpillar) directly, but instead attack larvae of other parasitoids already feeding inside the host. In other words they are parasitoids of parasitoids.
Parasitoidception.
Watch this excellent video explaining the complex relationship between several wasp species living on a tobacco hornworm:

This can explain the intense antennation performed by the Brachymeria wasp on the caterpillar for a long period of time. Maybe the wasp was trying to determine if there are parasitoid larvae already present in there. One of the most common sights when it comes to infected hawkmoths is a caterpillar with a cluster of white silk cocoons dangling from its body. Those cocoons belong to braconid wasps, and there is a good chance that the Bracymeria wasp was after their larvae, as some species of in the genus are parasitoids of Braconidae. The golden Conura wasp could then compete for access to those parasitoid larvae or even go after the Brachymeria larvae. It can get pretty complicated with chalcidid wasps.

Hawkmoth caterpillar with cocoons of a braconid parasitoid wasp. The caterpillar is still alive, and can move its head to deter predators like ants and other parasitoids from approaching the developing wasps.

Hawkmoth caterpillar with cocoons of a braconid parasitoid wasp. The caterpillar is still alive, and can move its head to deter predators like ants and other parasitoids from approaching the developing wasps.

So who won in the end? The wasp that was more persistent. At the end of the fight the black Brachymeria wasp was nowhere to be seen, and the golden Conura wasp took over the caterpillar and started antennating it.

The winning chalcidid wasp (Conura sp.) with its hawkmoth caterpillar prize

The winning chalcidid wasp (Conura sp.) with its hawkmoth caterpillar prize

The interesting thing here is that members of genus Conura are usually associated with butterfly and moth’s pupae, yet the wasp here decided to chase off a competitor and take over a caterpillar.

Chalcidid wasp (Conura sp.) on a swallowtail butterfly pupa

Chalcidid wasp (Conura sp.) on a swallowtail butterfly pupa

Chalcidid wasp (Conura sp.) on a swallowtail butterfly pupa. This innocent face hides a dark secret.

Chalcidid wasp (Conura sp.) on a swallowtail butterfly pupa. This innocent face hides a dark secret.

Unfortunately, I had to leave the scene to catch a bus so I could not continue following this interaction. Without further observations, it is difficult to say with certainty what exactly was going on between the two wasps and the hawkmoth caterpillar. Parasitoids are so diverse, and many species have such complex biology. Even though several chalcidid wasp species are being studied closely as potential biological control agents, there are far more species out there about which we simply don’t know enough!

 

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

The Plot Thickens: Staring into the eyes of a dying Cephalotes

If you are an entomologist or an insect enthusiast, it is highly probable that you like ants. It is hard not to be impressed with their diversity, abundance, complex social structure and behaviors, as well as their interactions with other organisms. Ants are everywhere and do almost anything you can think of. To most people however, ants could not be any less exciting. They are often seen as a generic insect, with a relatively uniform appearance. They always show up when unwanted, find their way into our homes, take refuge in dark and hard to reach corners, and steal our food.
I like ants. I think they are fascinating creatures. But every now and then I find myself talking people into looking beyond “that boring-looking ant”, to try and catch a glimpse of their busy life. It is not always easy to communicate ants to the public (which is why I praise myrmecologists – people who study ants for a living), however I find that it is quite easy in the case of one ant genus in particular: Cephalotes.

Turtle ant (Cephalotes atratus) from the Ecuadorian Amazon

Turtle ant (Cephalotes atratus) from the Ecuadorian Amazon

Cephalotes is a large genus of arboreal ants found in the neotropics. There are over 130 species, all inhabit tree hollows or utilize cavities in other plant tissues. Looking like they were designed by someone with overflowing imagination, they easily come off as cute. Their flattened head and armored body, often decorated with long sharp spines for protection, their thick legs and perfectly round abdomen, along with their matte color finish, give them the appearance of a plastic toy. In addition, Cephalotes ants move relatively slowly and cannot bite or sting, making them user-friendly. Can you ask for a more perfect ant?

The queen turtle ant (Cephalotes atratus) is bigger and bulkier than her workers. She also lacks the defensive spines.

The queen turtle ant (Cephalotes atratus) is bigger and bulkier than her workers. She also lacks the defensive spines.

Turtle ant worker (Cephalotes atratus) foraging on a mossy tree trunk

Turtle ant worker (Cephalotes atratus) foraging on a mossy tree trunk

They are commonly known as turtle ants, but also got the name gliding ants, thanks to their incredible ability to parachute from high in the canopy and land back on the trunk of their home tree. Their unique body structure and flattened legs allow them to slow down and change their course while falling (some spiders can do the same, by the way). In some species the soldier cast evolved a large head to function as a living door, plugging the entrance to the nest.

Turtle ant soldier (Cephalotes sp.) from Colombia, showing a heavily armored body and a massive head

Turtle ant soldier (Cephalotes sp.) from Colombia, showing a heavily armored body and a massive head

The same turtle ant soldier (Cephalotes sp.) from the previous photo. These ants are built like tanks.

The same turtle ant soldier (Cephalotes sp.) from the previous photo. These ants are built like tanks.

In regards to interspecific interactions, Cephalotes ants are often seen tending sap-sucking hemipterans such as membracids and small fulgorids to gain access to sugary secretions from those insects. They also act as the model in a mimicry complex, where crab spiders masquerade as the ants in order to sneak up and prey on them.

Cute Cephalotes workers visiting a camouflaged fulgorid planthopper nymph

Cute Cephalotes workers visiting a camouflaged fulgorid planthopper nymph

Portrait of a turtle ant (Cephalotes atratus). How can you not fall in love with them?

Portrait of a turtle ant (Cephalotes atratus). How can you not fall in love with them?

Did I mention they are cute? I have written before that you should never become too attached to insects you encounter in the field. And as much as I love the adorable Cephalotes ants, it is important to remember that there are many dangers lurking for them in the forest. During my recent trip in Colombia, I stumbled upon a Cephalotes nest in a tree outside my room. The ants were very active and did not present good photographic opportunities.

Turtle ant (Cephalotes sp.) from Colombia. How adorable!

Turtle ant (Cephalotes sp.) from Colombia. How adorable!

One of them however, stood out among the rest. There was something different about its behavior. This worker moved franticly in what appeared to be an aimless run. It did not follow the other workers, and seemed more interested in reaching a higher spot on the tree. I collected the ant for a closer look, and once I inspected her carefully I believe I found the culprit for her unusual behavior. This ant had a reddish abdomen, as opposed to the black abdomen of her sisters. The red color, coupled with erratic behavior suggests this worker has been infected with a parasite, a nematode worm.

Turtle ant (Cephalotes sp.) infected with a parasitic nematode worm, showing a swollen red abdomen. Compare to the healthy worker in the previous photo.

Turtle ant (Cephalotes sp.) infected with a parasitic nematode worm, showing a swollen red abdomen. Compare to the healthy worker in the previous photo.

The parasitic worm lives and breeds inside the body of birds, which spread the worm’s eggs in their droppings. The ants collect nutrients from the bird droppings (along with the eggs) and feed them to their larvae, where the worm matures. In order to complete its life cycle the parasite needs to return into a bird’s body, so it changes the host ant’s appearance to look like a ripe red fruit, and causes it to climb higher on the tree to become more accessible to hungry birds. As much unique character this worker ant might have had, the sad truth is that it was destined to die prematurely. And there was nothing I could do about it. There is a great lesson here – sometimes, the raw essence of nature is difficult to take in. We would like to see it as a peaceful place where all the animals and plants live together in harmony. But the reality is that nature is harsh. It is full of conflict, violence, disease, and death. And we must accept it as an integral part of the world we live in.

Cephalotes ants offer a great opportunity to peek into the life of a small insect and learn about its survival (as well as failure) in various habitats. Before I end this post, there is one thing I would like clarified – going back to their name, why did Cephalotes get the name turtle ant, whereas some leaf beetles were named tortoise beetles? Is there any justification for the turtle designation when it comes to the ants? After all, both insects are terrestrial. If there is an etymologist in the audience, maybe you can help the entomologist?

 

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!

Rhynchotermes – the best of both worlds

If you read my previous post about blattodeans you might have noticed that I left something out. The post does not make a single mention of termites that belong in the same insect order. Yet my Blattodea gallery contains photos of some termite species. What is going on?

Make no mistake – termites are indeed included in order Blattodea. While they do not lay their eggs in cases (oothecae), they share many other attributes with roaches. Historically, termites were classified under their own order, Isoptera. This is what I learned at university during my entomology training a decade ago. However, times change, and with it taxonomy is rearranged according to new evidence concerning the relationships between groups. Termites have been found similar in their morphology and social behavior, as well as molecular phylogenetics, to wood-feeding roaches of the genus Cryptocercus, and both are now treated as sister groups under the infraorder Isoptera within the Blattodea. I will only say that although I welcome this update in termites’ taxonomical position, I found it difficult to get used to at first. Old habits die hard I guess.

Termites are truly unique because they are among the few hemimetabolous insects (lacking the pupal stage in their life cycle) to develop an eusocial lifestyle, with different reproductive castes, division of labor, and overlapping generations. In stark contrast to eusocial Hymenoptera (ants, bees, and wasps), termite colonies follow a different structure, often with a single long-lived royal pair responsible for egg production (as opposed to male Hymenoptera that die soon after mating), but also include a secondary reproductive caste. Workers and soldiers can be both males and females (in Hymenoptera – all females). From an ecosystem standpoint, termites play a vital role as detrivores, feeding on and breaking down dead plant tissue and wood. For this reason they rely on gut symbionts (protozoans, bacteria, and flagellates) that assist in breaking down cellulose.

One of the things you often learn about termites in an entomology course is that there are two types, easily distinguished by their soldiers: species with mandibulate soldiers (possessing jaws), and species with nasute soldiers (with a long nose). The mandibulate soldiers use their enlarged strong mandibles to physically attack and injure intruders. They cannot use their jaws for feeding, and are therefore dependent on mouth-to-mouth feeding from the workers. In contrast, the nasutes deploy chemical defense by secreting various compounds from their nose, mainly to use as deterrents against ants, but also with some effect over much larger predators such as tamanduas.

Why this long introduction? As things usually go in nature, and more specifically in arthropods, to every rule there is an exception. Last year I travelled to Costa Rica, and one of the species I was hoping to find was a very unique termite.

Armed nasute termite soldier (Rhynchotermes perarmatus)

Armed nasute termite soldier (Rhynchotermes perarmatus)

This monstrous beast is a soldier of Rhynchotermes perarmatus, a nasutiform termite. However, contrary to the “rule” I mentioned above, soldiers of this species possess both a chemically armed snout and well developed mandibles. They are now treated by taxonomists as being mandibulate nasute.

The neotropical genus Rhynchotermes contains several species, all have nasute soldiers with noticeable mandibles. However, only in two species the mandibles are massive – Rhynchotermes perarmatus and R. bulbinasus.

Armed nasute termite soldier (Rhynchotermes perarmatus). Combining elements from both nasute and mandibulate termites!

Armed nasute termite soldier (Rhynchotermes perarmatus). Combining elements from both nasute and mandibulate termites!

Rhynchotermes perarmatus is subterranean, nesting underground or under stones. These termites usually do not expose themselves to the outside world, but instead move inside covered tunnels constructed from soil particles. Inside these dark tunnels the stout workers run clumsily, carrying debris and compressed wood fiber back to the colony for food.

An intimate look at Rhynchotermes perarmatus termites crawling in one of their covered nest tunnels

An intimate look at Rhynchotermes perarmatus termites crawling in one of their covered nest tunnels

An active tunnel contains a thick flow of worker termites, and several soldiers scattered at the periphery, on guard.

An active tunnel contains a thick flow of worker termites, and several soldiers scattered at the periphery, on guard.

Rhynchotermes seems to be associated with slightly disturbed habitats, such as cleared forest areas or meadows used for cattle grazing. There are reposts of them active under aged dried out cattle dung, suggesting they may have a role in breaking it down and recycling the nutrients. In Costa Rica I found Rhynchotermes perarmatus under a heavily decomposed fallen tree, right besides a well-maintained trail. Still, after flipping the log I could not see them. I had to break open one of the galleries to get access to the action.
And the soldiers did not like that.

Armed nasute termite soldiers (Rhynchotermes perarmatus) crawling out to defend the workers

Armed nasute termite soldiers (Rhynchotermes perarmatus) crawling out to defend the workers

While the workers kept on running seemingly undisturbed, the armed soldiers started pouring out, seeking the intruder. Maybe this is the time to mention that termite soldiers are usually blind. They have no functional eyes, and rely on chemical cues and physical proximity for defending the colony.

"Fear me, ant!"

“Fear me, ant!”

Even tough beetles like this weevil know to steer clear of active Rhynchotermes perarmatus soldiers.

Even tough beetles like this weevil know to steer clear of active Rhynchotermes perarmatus soldiers.

To the human eye it seems like despite their menacing appearance, Rhynchotermes perarmatus soldiers do not do much. They walk around aimlessly, then suddenly rise on their feet and give a mute roar, gaping their mandibles. But what seems harmless to us is actually a well thought of strategy: the soldier’s head contains a special gland that secretes a cocktail of sticky odorous compounds from an opening located in the snout. It is easy to think of nasute soldiers as nozzle heads discharging glue, but in reality what Rhynchotermes discharge is a strand, not fluid. The idea behind this is to turn your enemy into a sticky mess and incapacitate it. This is effective in case of attacking ants, perhaps termites’ worst enemies. The chemical properties of the compounds may also have a role in disrupting the ants’ chemical communication. Sometimes during the interaction the termite soldiers stick to the ants as well, sacrificing themselves for the benefit of the colony. But what if this does not work? Then they can use their secondary weapon – the mandibles.

Armed nasute termite soldier (Rhynchotermes perarmatus) gaping its impressive mandibles

Armed nasute termite soldier (Rhynchotermes perarmatus) gaping its impressive mandibles.

The mandibles are curved (similar to those found in army ant soldiers) and double-hooked. I cannot help seeing them as reminiscent to the mandibles of young Epomis larvae. This is probably an adaptation to grab and hold on tight to whatever the termite is biting. I even tested it – not only the soldiers grab well, they also lock themselves in place. They are difficult to pull out, like a fishhook.

Let me tell you, these tiny soldiers can sure bite!

Let me tell you, these tiny soldiers can sure bite!

Another thing I noticed is that many soldiers had “broken noses”. I wonder if the snout has a breaking point to allow for a quick release of the gland’s contents onto the intruder. They too moved about clumsily looking for troublemakers to the colony, reminding me of a drunken guy trying pick a fight in a bar, broken bottle in hand.

Poor soldier got its nose broken

Poor soldier got its nose broken

Aren't these termites just stunning?

Aren’t these termites just stunning?

There is still much we do not know about Rhynchotermes. For example, in the case of Rhynchotermes perarmatus, the alate caste was described only recently. Some Rhynchotermes species tend to occupy abandoned nests of other termites, but occasionally they are also found in close proximity to active nests, bordering the neighbouring colony or right on top of it. It would be interesting to examine what kind of interaction they have with other termite species. Like a lot of things in nature, these termites do not conform to our neat labels. Their bizarre soldiers represent the best of both worlds. They serve as a reminder that nature is full of surprises, that rules are meant to be broken, and that you do not have to look hard to find something new and inspiring.

A Moment of Creativity: Reconsidering blattodeans

A while back someone asked me if I had any plans to put up a gallery page for blattodeans on this website. That was indeed something I had in mind; This is one of my favorite insect groups, so it would not do them justice if they are unrepresented here. I hate to admit, but my issue with uploading photos of blattodeans is mainly due to difficulties in identifying some of the species I photographed. Nevertheless, I am happy to report that the Blattodea gallery is now up and running.

Blattodeans suffer an extremely undeserved bad reputation. The majority of Blattodea species live in natural habitats such as forests, deserts, sand dunes, and meadows, leading a cryptic lifestyle away from humans. Only a tiny fraction of them, less than 1%, lives in proximity to humans and considered as pests. For this reason I decided to ditch the word “cockroaches” and follow Piotr Naskrecki by adopting the word “blattodeans”. In the sad reality that we live in today, the word “cockroach” often carries a negative connotation in people’s minds. It is associated with something unwanted, menacing, dirty, and harmful. This could not be further from the truth: many blattodean species help to break down decaying organic matter, making crucial nutrients available for other organisms. They are, along with ants and flies, nature’s cleaning service (you’re welcome). Some species are also important pollinators. And that is without even mentioning their numerous adaptations to avoid predators, their maternal care, and social behavior.

A forest blattodean nymph (Nyctibora sp.) with white "socks." If you don't think he's cute you might want to check your pulse.

A forest blattodean nymph (Nyctibora sp.) with white “socks.” If you don’t think he’s cute you might want to check your pulse.

A long time ago I had the idea of photographing blattodeans right after molting, while they are still fresh and pigment-free. My goal was to see whether people would recognize the animal presented to them, now that it lacks some of its identifiable characters. By the way, I have been doing the same thing with whip spiders.

Blattodean molting. Who knows what it is going to look like once pigmentation appears?

Blattodean molting. Who knows what it is going to look like once pigmentation appears?

The semi-transparent exoskeleton of a freshly molted Lanxoblatta rudis nymph allows a rare glimpse into the insect's internal network.

The semi-transparent exoskeleton of a freshly molted Lanxoblatta rudis nymph allows a rare glimpse into the insect’s internal network.

The first attempts were done with Periplaneta americana, a common species that most people associate with pests. When presented with an all-white Periplaneta, almost everyone said it looked “cute”.

Freshly molted male Madagascar hissing cockroach (Gromphadorhina portentosa)

Freshly molted male Madagascar hissing cockroach (Gromphadorhina portentosa)

Above is a freshly molted male Madagascar hisser (Gromphadorhina portentosa) from a colony we kept at the museum I worked at (for more details see my previous post). We used to isolate individuals that showed signs of an approaching molt, to use them in class displays for students. Large males like this one were always a special treat, with their impressive horns. I took this photo in 2006. Even though I have seen and photographed many freshly molted blattodeans, I still see this old photo as one of my best captures. There is something about it that speaks to people. They no longer recognize an insect they are repulsed by; instead many people see something that reminds them of a cat. Recently I was delighted to learn that this photo has provided inspiration for an artist: I stumble upon an article in Chinese encouraging people to learn more about blattodeans. It featured my photo (=copyright infringement), followed by a drawing of an innocent-looking girl wearing the male horned hisser as a hat. Cute girls with cat ears (referred to as nekomimi, or in the case of other animals’ ears – kemonomimi) is a popular theme especially in manga and anime in Japan, and the blattodean serves a similar purpose here. As a matter of fact, early on I gave my photo the title 猫ちゃん (neko-chan), which translates to “kitty” in Japanese.

Blattodean kemonomimi embeded from the article mentioned. Artwork by user 长得像人的割草机 on Weibo (see originals in the comment below)

Generally speaking, I find that a lot of people respond differently to white blattodeans compared to dark-colored ones. It is almost as if it is a completely different animal. What is it that makes us so susceptible to visual cues in the form of flat dark insects? There must be a reason for this sensitivity.

A molting forest blattodean (Nyctibora sp.) shows off its elegant golden wings

A molting forest blattodean (Nyctibora sp.) shows off its elegant golden wings

Some blattodeans are white by nature, like this beautiful species of Panchlora from Belize

Some blattodeans are white by nature, like this beautiful species of Panchlora from Belize

We used to joke at the museum that when it comes to human reaction, insects can be divided into two subgroups. The first subgroup contains “green” insects: these are insects that are perceived as friendly just by their appearance. They do not necessarily have to be green, but it helps if they are. This group contains ladybugs, grasshoppers, stick and leaf insects, smooth caterpillars, stout and furry moths, mantids, and katydids to some extent. The other subgroup contains all the other insects. Again, this division is merely a joke, but it is amazing to see just how many people follow this arbitrary division. To those who welcome ladybugs but put blattodeans in the “other” subgroup, I always remind that there are blattodeans out there that look exactly like ladybugs.

Male horned roach (Hormetica apolinari). Not as cuddly as the white "neko-chan", but pretty close.

Male horned roach (Hormetica apolinari). Not as cuddly as the white “neko-chan”, but pretty close.

Since photographing “neko-chan”, I have been working with other species of blattodeans, hoping to achieve the same result, however, I was not able to replicate that look. Maybe it was more than just timing the photo with the molting process. Maybe I also captured some of the hisser’s essence and unique personality. After all, he almost looks like he is trying to tell us something. Well, he does, all blattodeans do – but we never stop to listen.

Halloween special: My worst bug bite

Last week I gave a seminar in front of med students and doctors at Toronto’s University Health Network about medically significant arthropods. Because I am not a doctor I chose to focus more on the animals themselves, presenting their side of the story and what type of situations bring them to sting or bite humans. The talk went well, I was even able to share my first hand experience with botflies, which triggered some interesting questions from the students. After the talk, one of them approached and asked me – “So, what was your worst bug bite or sting?”
I replied that my body has a severe response to black flies and their bites, swelling like crazy that I can barely recognize myself in the mirror the day after. He seemed satisfied with my reply, however on my way back home it occurred to me that this was not the answer to his question. He did not ask me which bite or sting I disliked the most. He asked me of all the bites and stings that I’ve gotten so far, which one was the worst.
And that is a valid question. I have a history of getting injured while doing all sorts of stuff, and this includes an impressive list of arthropod bites and stings accumulated over the years. But there is one bite that holds the title “the worst”. One bite I will never forget.

Some background: Back in 2007 I took a trip to Ecuador with my colleague and mentor, Alex Shlagman. We worked together at Tel Aviv University’s Natural History Collections (now known as The Steinhardt Museum of Natural History), breeding local and exotic species of arthropods for research, teaching, and display purposes. As the manager of the live arthropods collection, Alex was, and still is, the best arthropods keeper in Israel. On the other hand, I had an extensive travel history under my belt, after crossing South and Central America a few years before. This experience gave me useful insights when tackling the husbandry needs of tropical insects we kept. Nevertheless, it bothered me that Alex, with his vast knowledge of those insects, has never experienced the rainforest and its staggering diversity in person. So I did something crazy and I decided to take him to Ecuador.

One of the places we visited was a biological station close to the Amazon region. Despite the heavy rainfall this area usually gets, it was extremely dry during our visit, which made it difficult to locate animals active during the day – it was just too hot. One afternoon we hung out close to the station’s access road, following leaf-cutter ants and other insects, and taking photos. While tracking leafhoppers I stumbled upon a bush covered with what seemed to be communal assassin bugs. They were quite unique in their appearance, with a shiny lime-green abdomen and black head and limbs. From a distance they looked like spiders.

Assassin bugs in ambush waiting for prey

Assassin bugs in ambush waiting for prey

I took a single photo and then I moved in to do something I knew I shouldn’t – I poked the bug with my finger to force it into a better “pose”.
And it got into a better pose alright, immediately grabbing my finger and punching a hole in it using its thick proboscis. The pain was so sharp that I remember falling backwards and landing hard on my buttocks, while the bug let go and escaped. I sat there, silent, holding my hand with a bitter expression on my face.

Maybe I should elaborate at this point. Assassin bugs are venomous animals. Their venom is rather complex and contains many compounds, some of which has neurotoxic properties that can lead to a systemic response (and so potentially may cause death). Some assassin bugs have venom so powerful that it is often compared to a cobra snake’s venom in its potency, easily causing paralysis in mammals much larger than the small bug. Holotrichius inessi, an assassin bug roaming the deserts of Africa and the Middle East is even known to hunt scorpions, which are feisty venomous animals themselves. That is an extreme example. The truth is, in most cases we do not know enough about assassin bugs and their venom potency. So when bitten, you just don’t know what to expect.

Black sand assassin bug (Holotrichius innesi) preying on a scorpion

Black sand assassin bug (Holotrichius innesi) preying on a scorpion

As I sat there trying to gather my thoughts about what has just happened, I felt numbed by the pain. You know how sometimes when something aches so badly you can feel it pulsating? I did not even feel that. I could not feel anything but pain. I thought to myself, this is it. This is how I go. Alex later told me it was the first time he ever saw me looking confused, like I was watching my life flashing before my eyes. To some extent it really felt this way. I could not speak and I did not want to move (from fear I would worsen my condition). I just wanted this to end. We were essentially in the middle of nowhere, with no one around, so we just waited it out. I cannot remember how long it took, as I really lost the sense of time, but I remember the pain eventually reducing to a dull itch. This is when we got up and left. The itch and stiffness stayed for a few additional days and then dissipated.

Just imagine this probe drilling into your finger. Not exactly fun, I can tell you.

Just imagine this probe drilling into your finger. Not exactly fun, I can tell you.

I always find it a bit funny that my worst bug bite actually is a bug bite. Ever since that trip I have been trying to find that species of assassin bug in my subsequent visits to Ecuador, but I always failed. It is slowly turning into my Moby Dick. The important lesson here is: kids, do not go around poking animals you do not know with bare hands. It has taken me a few more bites and stings until this lesson sank in. Nowadays I am much more careful in the field.
… and I still get bitten and stung.

Your personal opinion means nothing to nature

In the past month I have been involved in some pretty interesting conversations surrounding public perception of stinging and biting insects. This is in large part due to a talk I was preparing about medically significant arthropods (more on that in the next post). Some of the civilized discussions ended in surprising way for me, with a few people unfriending or unfollowing me on social media just because they could not understand my point. I am going to try and address the issues I opened by using excerpts from those discussions. I feel like this is going to end up being a ranty post, but I must do it. Feel free to chime in with your thoughts in the comment section – they are most welcome.

Examining a queen European hornet (Vespa crabro) found overwintering under a log.

Examining a queen European hornet (Vespa crabro) found overwintering under a log.

To put it simply, there are two topics I want to open:

1. “Aggressive” arthropods

The first discussion evolved after I shared a conversation I had with a twitter user about a photo of a wasp.
The guy immediately took the stance of “all wasps are aggressive”, and continued to give examples from his own experience of wasps nesting close to his window. I do not want to get into too many details (you can see that conversation in the screen grab), I will just mention that a) the photo showed a male wasp that is incapable of stinging, and b) the nesting wasps do not know they are using this guy’s window. They do not even know what a window is!!!
There seems to be some confusion surrounding the term “aggressive” when describing arthropods, and animals in general. Hippopotamuses are aggressive. Some bears are aggressive. Crows can be aggressive if you injure one of their members. I think you get my point. With arthropods, I am not sure I have a clear cut example of aggressiveness. Maybe “aggressive” is not the right word. Don’t get me wrong, venomous stinging animals are still somewhat dangerous and occasionally do land people in the hospital after being stung. But I ask you, when you call them aggressive, what do you mean exactly? Aggressive to who? Anyone within the range of a nest or just anyone? Do they chase and attack people without provocation? Who took the first step? Sometimes being too close to wasps triggers their defense behavior. But then again, you really have to rub it in their face and disturb them for this alarm response to occur.

Yellowjackets (Vespula germanica) feeding on a fallen pear

Yellowjackets (Vespula germanica) feeding on a fallen pear

For example, I was very close when I took this photo of the yellowjackets. The wasps were active all around me, and NOTHING happened. These wasps were very nice to me. Seriously, I do not understand why they have such a bad reputation. Don’t start nothing, won’t be nothing. I am not saying anyone else should try to do the same. That would be foolish, especially if you are not familiar with wasp behavior. But I would not call them aggressive. I see wasps and other stinging arthropods as “defensive”. I think the difference between aggression and defense is the presence of provocation. If an animal attacks without provocation, I would classify it as aggression. What is debatable is the definition of provocation. Clearly the meaning of it to us is different from that perceived by social insects. Do not forget that in their world chemical communication takes a substantial part. If the wind blows in their direction, carrying over our scent to the nest, that would be considered a provocation and will trigger a defensive behavior. Things are different if you accidentally hit a wasp nest. Then they will “aggressively” defend their nest.

For many people the sight of a hornet nest in their backyard is terrifying. But in reality these wasps are only interested in making it through the summer months.

For many people the sight of a hornet nest in their backyard is terrifying. But in reality these wasps are only interested in making it through the summer months.

Of course, no one can tell what goes on in a wasp’s mind. They cannot read our minds either. They do not know our intentions just as much as we do not know theirs. There has to be some sort of mutual respect if you want this to end peacefully. Unfortunately, that is something that a lot of people do not have towards nature today. People just see ‘wasp’ and go batshit crazy.

I agree that in some areas where they are invasive, wasps are a problem, particularly in islands. They forage on native fauna, spreading fast and wrecking havoc in their path. But is it aggressiveness? Or is it evidence that they are just very good at what they are supposed to do? It is just foraging and nothing more. Because they thrive in areas with no natural enemies, their food hunts may seem like the wasps are out of control, but they are really just doing their thing to survive and reproduce. Still, they need to be eradicated from these habitats, no doubt.

Going back to the meaning of the word “aggressive”, it shows how difficult it is to communicate without having a clear definition of the word. This is more a discussion about semantics than anything else. Now, I am guilty for being stuck in my own bubble with no idea how things are perceived by others. Each person has their own definition of what being aggressive is, and this is in part related to their personal experience as a human. As noted by a friend of mine, this is largely due to the unprovoked aggressiveness we know from human troublemakers and the unnecessarily violent overreaction that happens when someone thinks they took enough beating and lashes back out. I think the first step is to differentiate the use of the term “aggressive” for describing human behavior and animal behavior. Here is why I stopped using the term frequently when discussing animals:
It crates a negative outlook on nature.
We tend to bring our human-centric approach to nature. “Those animals are trying to hurt me”. “They built a nest on my property”. I understand that it is frustrating to discover a potentially injurious animal in one’s living space, if this had happened to me I would want them removed too. But we must learn to put ourselves out of the picture. Those animals are not there because of us. They are there because the harsh competition in nature is forcing them to do what they can to survive. It just so happens that our living space feels safe for them too, but can you blame them?

2. “Purpose” in the natural world

Perhaps one of the questions I get asked the most, even more often than which camera equipment I use, is what is the purpose of –insert pest species here-:
What is the purpose of flies?
What are mosquitoes good for?
What is the purpose of wasps in nature?

I think these questions stem from a very common human behavior. From an early age we have this innate, almost inexplicable urge to ask “why?” about everything. We are curious to break down how things work around us, and if the world is constructed from tiny pieces, then every piece must have its own purpose assigned to it.
The real question here is who assigns these purposes. Is it man? That would be a very anthropocentric view of life. Conversely, if you believe a purpose is assigned from above by an all-powerful being such as god, then you should not be asking an entomologist these questions. You should ask god. (go and do that right now. It’s OK, we’ll wait. Are you back? Good. Let’s continue) In contrast, if we look at the natural world from an evolutionary perspective, then yes, all the pieces have their rightful place in the big puzzle, otherwise they would not exist.

This is why I believe the questions mentioned above are phrased horribly. Using the word “purpose” suggests that there must also be a benefit to us, humans, to justify the existence of something. That is the wrong way to look at the world. This search for purposes, for meaning in everything, is a characteristic of human nature. Well, what is the purpose of humans then? Why are we here? This is not an easy question to answer when you start thinking about it seriously. Because one person may think humans are on this planet for one purpose, while another person will think of a different purpose for our existence. But let’s not get too philosophical and go back to arthropods and other pests.

What is the purpose of flies/mosquitoes/wasps/ticks/leeches?
To survive.
A better way to look at this would be to ask what role those animals play in nature. To this question there is a concrete answer, because every species has its natural history. The pest insects mentioned above break down organic matter, pollinate, and regulate the populations of other arthropods. I want to take this opportunity to give an example for such an inquiry gone totally wrong, and use it to forward the discussion and paint the bigger picture.

Last week I shared a photo of an African tick, Dermacentor rhinocerinus. The only reason I posted it was because I thought it was beautiful, and I wanted to show that it is possible to appreciate such an animal even though I would not want it to suck my blood.
To be honest, I already got used to getting hate comments and I expected some negative responses to arrive. And arrive they did.
Let’s analyze this conversation together.
In this first part of the conversation, a person leaves a comments that ticks are never beautiful, and that their existence has no justification. This a subjective statement, so I reply in the same manner. Then they go on by saying that ticks serve no purpose in the ecosystem, and that nature would be better off without them. This kind of comments make me cringe. If an organism exists right now as we speak, it means two things: it has a well-based role in nature, and it is extremely good at what it does.
I am copying my reply because I think it is worth reading:

The only thing that ticks do in nature, just like any other animal, is survive. That is the one job they have – to continue the existence of their species. They do so by feeding on blood of other animals. And by doing that (their “role”, if you wish), they dilute and remove the weak individuals from the mammalian population. Now, what is important to understand here, is that ticks do not exist to spread diseases. They are blood feeders. The disease pathogens come from mammals and birds. Ticks have no mutualistic relationships with the bacteria, viruses, and protozoans that they vector. Spreading diseases is more of an artifact of their feeding habits. You want a world without ticks? Fine, but just like you said ecosystems would adapt to their absence, those disease pathogens will continue to thrive in their mammalian hosts, and nature will find a way to get those diseases back into humans.
I’m going to take a risk by saying a world completely free of diseases is a world without life.

The next part is really interesting. After explaining that ticks belong in the natural world no less than other animals (as well as humans), the person who started the conversation goes back to their original stance. Suddenly they remember that they already know and understand everything that has been discussed so far, but they insist that ticks cannot be referred to as beautiful. It is blasphemy. What I find amazing is that this person accused me of having a naïve perspective of biology because I thought a tick was beautiful. This is coming from a person who spent much of his time breeding killifishes, a hobby fish that is praised and prized for its beauty. Oh, the irony.

Conclusion

What these two topics have in common is showing that people tend to bring a lot of their emotions into the conversation when they talk about arthropods they hate. I understand that you do not like insects and arachnids. I also understand that you feel like they are chasing you. However, please trust me when I say there is absolutely no stinging arthropod that is out to get you. They use their stinger for defense only. If you do feel like something is coming after you, please consult a physician or a psychiatrist – you might suffer from delusional parasitosis, entomophobia, or arachnophibia (all totally normal, and treatable by the way!). Also please be aware that there are people out there who find these creatures fascinating and beautiful, even pest insects like mosquitoes. If they can do it, maybe these bugs are not so bad after all? Give them a chance. You may find that the fear and hate you experience are only a manifestation of not knowing enough about these animals. And at the very least, be respectful and compassionate to other people, even if they hold a different opinion than yours.
At the end of the day, your personal opinion means nothing to nature. Nature will continue to function regardless of what you feel. You know what does mean a lot to nature? Your actions.

 

Compsus: glitter weevils with structural coloration

The insect world is full of great examples for flamboyant insects. From mosquitoes sporting feathery legs and electric blue scales, through the splash of vibrant colors in rainbow katydids, to shiny golden-green orchid bees and their mimics. But none are as dazzling as the glitter weevils of genus Compsus (family Curculionidae, subfamily Entiminae).

Short-snout weevil (Compsus sp.) from Mindo, Ecuador. It is hard to take all these colors in.

Short-snout weevil (Compsus sp.) from Mindo, Ecuador. It is hard to take all these colors in.

Compsus is a large genus distributed mainly in Central and South America, with one species occurring in North America. It contains around 140 species, mostly small to medium sized beetles of 0.5-2.5cm in length. Several species are considered as pests of citrus trees. The adult weevils feed on plant tissue: leaves, flower petals, and pollen, but they will also go for rotting leaves and fermenting fruits. The females oviposit egg masses on the aerial parts of trees. The young legless larvae hatch, drop to the ground, and burrow into the soil where they feed on the roots of the tree. At the end of its developmental stage the larva builds a chamber in the ground and pupates, and it will stay in this state for two months until the adult’s eclosion. Compsus weevils complete their life cycle within 5-7 months.

Another species of Compsus from Mindo, this one has a bit more metallic sheen to it.

Another species of Compsus from Mindo, this one has a bit more metallic sheen to it.

Compsus weevil feeding on rotting plant tissue

Compsus weevil feeding on rotting plant tissue

Freshly-eclosed short-snout weevil (Compsus sp.) use impressive mandibles to break out of the pupal skin. These scissor-like attachments drop later.

Freshly-eclosed short-snout weevil (Compsus sp.) use impressive mandibles to break out of the pupal skin. These scissor-like attachments drop later.

But what makes Compsus weevils so special, as well as other members of subfamily Entiminae, is their eye-catching colors. I would do these beetles a disservice if I didn’t explain where the colors come from, so things are about to get technical. Animal coloration is derived from spectrally selective light reflections on the outer body parts. There are two types of coloration:
1) Pigmentary (or chemical) coloration – occurs when pigments absorb scattered light in a narrow wavelength range. This type of coloration is the most common in animals.
2) Structural (or physical) coloration – achieved by nanometer-sized structures with changing refractive indices, causing coherent light scattering. Structural coloration is less common in the animal kingdom but it is widely encountered as well, and often structural colors are modified by spectrally filtering pigments.

Scales containing photonic crystals on the head of a Compsus weevil

Scales containing photonic crystals on the head of a Compsus weevil

Scales containing photonic crystals on the body surface of a Compsus weevil

Scales containing photonic crystals on the body surface of a Compsus weevil

The structures causing the physical colors are referred to as photonic crystals if they have properties (periodicity) that align with wavelengths of visible light. One-dimensional photonic crystals consist of parallel thin film layers of alternating high and low refractive index materials. These structures create the metallic and polarized reflections of cephalopods skin, the elytra of jewel beetles and scarabs, and the breast feathers of birds of paradise. Two-dimensional photonic crystals are structures with periodicity in two dimensions. An example for two-dimensional photonic crystals in animals would be the coloration of peacock feathers. Three-dimensional photonic crystals have been found in the scales of weevils and other beetles, but also in butterflies like the blue morpho.

Scales containing photonic crystals on the body surface of an Entiminae weevil (Eupholus schoenherri) from Indonesia

Scales containing photonic crystals on the body surface of an Entiminae weevil (Eupholus schoenherri) from Indonesia

Scales containing photonic crystals on the body surface of an Entiminae weevil (Eupholus schoenherri) from Indonesia

Scales containing photonic crystals on the body surface of an Entiminae weevil (Eupholus schoenherri) from Indonesia

Scales containing photonic crystals on the body surface of a Compsus weevil

Scales containing photonic crystals on the body surface of a Compsus weevil

Blue scales on the leg tarsus of an Entiminae weevil (Eupholus linnei) from Indonesia

Blue scales on the leg tarsus of an Entiminae weevil (Eupholus linnei) from Indonesia

In the case of Entiminae weevils, the adult beetles have strikingly iridescent scales, sometimes immersed in pits on the weevils’ elytra and legs. This gives the weevils a festive glittery look, as if they were covered with confetti during a big party. The reason for the bright coloration in weevils is mostly misunderstood. In some ways it may serve as camouflage in green species, but blue-colored species are very conspicuous so it remains unclear whether they advertise something to potential predators. I cannot complain: for me it is always a joy to see the cute Compsus weevils in the wild, even though sometimes it makes you feel like you missed out on a celebration or something.