mimicry - Gil Wizen

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 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

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.

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 allows 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

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

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.) 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?

Spiderception: jumping spider-mimicking jumping spider (Parnaenus sp.)

After a long hiatus of nearly 5 months, I thought it is about time I shake the dust off this blog and return to posting. This month we are celebrating Arachtober, highlighting spiders and other arachnids to promote appreciation and understanding that these animals are crucial to the normal function of ecosystems, and that they have their rightful place on this planet. Today is also International Jumping Spider Day, so it is a great opportunity to discuss something interesting that some of these cuties share.

Last February I was fortunate to spend a week in Colombia for a photography assignment. In one of our day hikes I checked a cluster of hanging vine flowers to see if there are interesting insects hiding inside. I did not find any insects except for ants, but as I was peeking inside the inflorescence I saw a row of shiny eyes staring back at me. I thought to myself – Oh, cool. A jumping spider. And indeed it was a salticid spider, however what I thought were eyes was nothing but a deception. In fact the spider’s head was facing away from me, and it was busy munching on a small moth.

Male Parnaenus jumping spider playing peek-a-boo. These spiders become even more interesting when viewed from behind.

Lateral view of a female Parnaenus jumping spider from Colombia. The color pattern on the abdomen resembles jumping spider eyes.

Female jumping spider (Parnaenus sp.). They are much cuter when looking straight at you!

Even though there are almost no identification keys for jumping spiders from the neotropics, I am confident that the spider I found was a female Parnaenus. For the most part these are plain looking jumping spiders, but their abdomen is usually covered with blue and green iridescent scales. On both side of the abdomen they have a row of spots that look exactly like jumping spider eyes. In fact, due to the contrast with the colorful abdomen, those spots are even more noticeable than the spider’s actual eyes. And it’s not just the female Parnaenus that possess these spots; the smaller and more colorful males have them too.

Male Parnaenus jumping spider. Huge head with stunning iridescent colors.

Dorsal view of a male jumping spider (Parnaenus sp.). From this angle you can see how easy it is to mistake the spots on the abdomen for eyes.

Jumping spiders are visual creatures. They rely on visual cues and their good eyesight to detect prey, competitive conspecifics, and potential mates. This is why many species of jumping spiders developed complex color patterns to assist in communication with other individuals. Other arthropods also take advantage of this and deploy mimicry to fool these spiders and avoid predation. One of the most common jumping spider mimicry is the presence of eyespots arranged in a row, to resemble the spiders’ large frontal eyes. I have already written about such cases on this blog, usually demonstrated by moths, but other insects as well (see here and here for examples, or check this paper for a summary). This mimicry seem to exist in some non-salticid spiders as well. On the other hand, we have also seen jumping spiders using mimicry to resemble insects. What we have not seen yet though, is jumping spiders mimicking jumping spiders. Is this even possible? Well, yes and no.
Yes, because there are definitely jumping spider species that display a clear salticid eyespot pattern away from their head where their actual eyes are – like the Parnaenus species presented in this post. And no, because we have no evidence that they are truly mimicking other jumping spiders.

Male Parnaenus jumping spider. So pretty.

A closer look at the abdomen of a male Parnaenus jumping spider. False eyes between green and blue scales.

This spiderception is quite confusing. At first it looks like the salticids deploy a “false head” anti-predator tactic in order to fool their predators and direct their attacks away from the animal’s real head. But in the case of these spiders the eyespots pattern is located on the abdomen, the most vulnerable part of the spider’s body. On the other hand, if they really use this pattern to communicate with other jumping spiders, we would expect to see a specific behavior associated with it, like waving the abdomen or displaying it in front of another individual. And to the best of my knowledge there are no such observations in existence.

Male Parnaenus jumping spider from Colombia

Parnaenus is not the only jumping spider genus that has eyespots on its abdomen, by the way. Other dendryphantine jumping spiders possess this character, to varying degrees. Those include the beautiful Paraphiddipus and Metaphiddipus jumpers and the scorpion spiders of genus Lurio. The latter is a very unusual jumper – the forelegs are disproportionally robust and long compared to the others, both in males and females.

Female scorpion spider (Lurio sp.) guarding eggs. Taironaka, Colombia

Scorpion spiders (Lurio sp.) have a color pattern on their abdomen that is very similar to that of Parnaenus spiders.

Female scorpion spider (Lurio sp.) guarding eggs. Even without the pretty colors these spiders are very unique, with their long thick forelegs.

The salticid eyespot pattern is quite common in nature, and it seems that possessing it positively affects the bearer’s chances of survival. Even jumping spiders themselves have it on their body. But do they really use it for active communication? Or is it more a passive way for them to say ‘I am a jumping spider inside and out’? Those are questions that are still left unanswered, at least until someone follows and documents their behavior.

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 31^st). 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 10^th. 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

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

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

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

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

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

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.

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…

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.

Jumping spider mimicry in Brenthia moths

Many insects deploy mimicry to fool their predators into thinking they are highly defensive, venomous, or simply not to be messed with. A great fraction of mimicry cases involve adopting the appearance of ants, wasps, and spiders for these exact reasons. One of the most interesting cases, however, is predator mimicry: insects that take the appearance of their potential predators in order to expose them. I have already written about one such case in crambid moths, but in this post I want to present one of the classic examples for this mimicry in metalmark moths of the genus Brenthia.

At first glance, metalmark moths do not really resemble spiders. In my post about Petrophila moths I mentioned that observed spider mimicry might also be a case of pareidolia. In other words, we as humans seek familiar patterns surrounding us, so we recognize the image of a spider on the wings, but is it really mimicry? And indeed, after posting I was accused of having a strong imagination for thinking this is mimicry. There is a good point being made here – in the case of Petrophila there is a temporal barrier preventing the two from encountering each other under normal conditions. Petrophila moths are nocturnal while jumping spiders are diurnal. Nevertheless, the prevalence of such wing patterns in the insect world suggests that they have a role in the survival of those organisms.

Metalmark moth (Brenthia hexaselena) displaying its typical body posture, with wings raised like a peacock’s tail.

Brenthia moths are no different. It takes some imagination to strip them off their mothy characteristics to see the resemblance to jumping spiders. Members of family Choreutidae, the genus contains over 80 described species, all sharing the same appearance: a unique body posture, and wings patterns that are reminiscent of jumping spiders’ eyes. In fact their common name, metalmark moths, is due to the convincing “catchlight” area of the eyespots, often consisting of silvery scales. Brenthia species also move like jumping spiders, advancing by short bursts of movements while still retaining their wing display. Lastly, these moths are diurnal and can be seen active on top of leaves, just like salticid spiders. If you think it ends there for these moths in regards to anti-predator defenses, let me also add that their caterpillars deploy defense strategies as well. When alarmed, they launch themselves through holes chewed into the floor of their webbed feeding shelter, giving the term “teleporting through a wormhole” a new meaning.

Metalmark moth (Brenthia hexaselena) in frontal view, displaying wing patterns that resemble a jumping spider’s face and legs.

Brenthia moth (upper image) mimics jumping spiders (lower image) with wing markings, wing positioning, and posture. Figure from Rota and Wagner 2006 (drawing by Virginia Wagner).

Portrait of a jumping spider (Phiale formosa). It is a little difficult to see the resemblance to the moth’s wing patterns, but the important thing is that it works to the moth’s benefit.

When discussing animals mimicking their predator, it is important to remember that we humans are not the target audience. This means that the imitator may not look too convincing in its mimicry to us, but still manages to trigger a desired response from said predator. However, when in doubt, the best way to know for sure is to put the suggested mimicry to the test through a series of experiments. Brenthia moths have become one of the best examples of spider-mimicking moths, thanks to rigorous testing. In their classic paper, Rota and Wagner placed the moths with their potential predators, jumping spiders of the species Phiale formosa, in arenas and recorded the outcome. They also used non-mimicking moths of the same size as control for the experiments. The results showed that the jumping spiders respond to Brenthia by displaying territorial behavior and waving their forelegs. In other words, upon noticing the Brenthia moths the spider predators immediately expose themselves. It comes as no surprise that Brenthia moths had a high survival rate in the experiments, as they could take off once the danger was revealed, avoiding predation. The control moths did not trigger a territorial response from the spiders and were preyed upon extensively.

Jumping spider (Phiale formosa) displaying territorial behavior in response to its own image. This is when the moth knows it is in danger.

One thing to keep in mind though is that this mimicry works well only because salticids are special among spiders. They do not make a web to capture prey, but instead rely on their excellent vision to detect prey. They are active predators, and therefore display a wide array of behaviors to communicate with other salticids. Jumping spiders will avoid other jumping spiders due to the risk of cannibalism. Brenthia moths take advantage of this behavior to get the higher ground by delaying the spider’s attack in order to escape. This makes them one of nature’s greatest con artists, but when survival is on the line, anything is kosher.

Papers mentioned in this post:

Rota, J, Wagner DL (2008) Wormholes, sensory nets and hypertrophied tactile setae: the extraordinary defence strategies of Brenthia caterpillars. Animal Behaviour 76(5): 1709-1713
Rota J, Wagner DL (2006) Predator Mimicry: Metalmark Moths Mimic Their Jumping Spider Predators. PLoS ONE 1(1): e45. https://doi.org/10.1371/journal.pone.0000045

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

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.

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

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

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.

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?

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)

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!”

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.

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

The nymph (Pycnopalpa bicordata) in full katydid-mode

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 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.

Vestria – the katydid that wanted to be a spider

Last week my home country celebrated the holiday of Purim; a holiday of joy, in which people go out to the streets, pretend to be something else by wearing masks and costumes, and exchange gifts. It is kind of like a happy mishmash of Halloween and Saint Patrick’s Day. And what excellent time it is to highlight interesting cases in nature in which one organism pretends to be another. One such story involves a genus of beautiful katydids – Vestria.

Rainbow katydid (Vestria sp.). It is hard to describe how colorful these katydids are. This photo does not do justice to the insect’s beauty.

When searching for arthropods in the rainforest I made a habit of backlighting leaves with a flashlight to see if there are animals hiding on the side opposite to me. There is always something interesting to find: salamanders, caterpillars, insects infected with parasitic fungi, and even velvet worms. Very often spiders occupy the underside of a leaf by day, waiting for nighttime to resume hunting on the top of the leaf’s surface. Among the most frequently encountered ones are huntsman spiders (family Sparassidae) of the genus Anaptomecus. These are flat, thin-limbed spiders, usually pale green in color to blend in with the leaf they are sitting on, but with a brightly colored abdomen with red and yellow patches. They are extremely fast, and when disturbed they shoot and vanish on the underside of a neighboring leaf.

Huntsman spider (Anaptomecus sp.). Amazon Basin, Ecuador

Huntsman spider (Anaptomecus sp.) hiding under a leaf

To my surprise, in some of these searches upon shining my light I thought I found a spider at first, but when I turned the leaf I saw a katydid nymph.

Katydid nymph hiding under a leaf. Like Anaptomecus spiders, they too seem to prefer sitting on palm leaves.

With the kind assistance of Piotr Naskrecki I learned that these are nymphs of Vestria katydids, known mostly due to their characteristics as adults (more on that later). Genus Vestria contains four species known from lowland forests of Central and South America, but do not let this low number fool you. There are many more species in need of a formal description, and others awaiting their discovery. In fact, to the best of my knowledge, all the species featured in this blog post are undescribed.

Rainbow katydid nymph (Vestria sp.) camouflaged on a leaf. Amazon Basin, Ecuador

The young Vestria nymphs bear an uncanny resemblance to Anaptomecus spiders. They too are flat, green with similar leg patterns, and have a bright yellow-red abdomen. Their mimicry to the huntsman spiders does not end there: they also share the same behavior of pressing flat against the underside of a leaf when resting, and running to the next leaf when disturbed. And, as I learned the hard way, they can bite. Like most members of tribe Copiphorini, Vestria katydids are packed with powerful jaws, and they will not hesitate to use them when in danger. By the way, these katydids are omnivores, feeding on both animal and plant matter, but they show a strong preference towards live prey, kind of like… well, spiders.

Rainbow katydid (Vestria sp.) feeding on a beetle pupa. When given a chance they will always prefer a protetin-based diet.

As adults, the Vestria katydids take a different look completely. They are no longer flat and look like the huntsman spiders. In this stage they are known as rainbow katydids or crayola katydids because of their striking coloration, which is an advertisement of their chemical defense against predators.

A selection of rainbow katydids (Vestria spp.) from the Amazon Basin of Ecuador

When provoked, Vestria katydids curl their body and hunker down, revealing a brightly colored abdomen. They also expose a scent gland from their last abdominal tergum and release a foul odor that is easily detectable from a close distance. Different species of Vestria have different odors, and from my personal experience I can attest that some species smell as bitter as bad almonds while others smell like a ripe peaches. The compounds released are pyrazines, and there is evidence that this chemical defense is effective against mammalian predators such as monkeys. While many katydids have bright aposematic coloration, Vestria species are one of the only examples of katydids successfully deploying chemical defense against predators, making them distasteful. But don’t listen to me, I actually like peaches.

Rainbow katydid (Vestria sp.) displaying defense behavior.

But let’s go back to the spider-mimicking katydid nymphs. As it is often the case in nature, mimicry is not always straightforward. Why would a katydid nymph adopt the look and behavior of a spider? Avoiding predators may be the answer that comes in mind, however it is not that simple to explain. Although the model spiders are venomous, they are easily preyed upon by the predators they share with the katydids – birds, frogs and lizards. So what other benefits come into play here? And is it really a case of mimicry? It is a difficult question to answer, as there are several possible explanations for mimicry in this is a case. To put it into context, on one hand it can be an example of Batesian mimicry, in which one harmless organism adopts the appearance of another that is widely-recognized by predators as toxic, vemonous, or unpalatable, to gain an advantage when confronted with a predator. In other words, the katydids use their mimicry to signal visual predators (such as spiders, mantids) to avoid confrontation with a spider (I discussed a similar case here). On the other hand, it might be a case of Müllerian mimicry, two unpalatable organisms evolve to look similar in appearance, to send the same message to predators and enemies. It is possible that both the Vestria nymph and the spider are signaling that they are fast-moving and can deliver an unpleasant bite when provoked. In addition, both have some sort of chemical defense: the spider is venomous, while the katydid is distasteful. There is also a third option – that this is all coincidental, and it is a case of convergent evolution: the two organisms simply try their best to hide from predators and came up with a similar adaptation to solve a similar problem, without mimicry. Piotr suggested that this is simply a crypsis (camouflage) adaptation for the two organisms. The yellow-red spots can represent leaf damage that is commonly seen on leaves in the rainforest. It just goes to show that in nature things are not always easy to explain, because sometimes they do not fall neatly into our boxes of labeled natural phenomena. What do you think?

Vestria nymphs have beautiful markings on their body, which can assist in breaking the outline of the insect to avoid detection by predators.

In some species the dark markings remain also in the adult stage.

Smile! You’re on katydid camera!

UPDATE (14 May, 2017): Paul Bertner photographed this amazing butterfly pupa in the Chocó rainforest of Ecuador. It bears an unbeatable resemblance to the Vestria katydid nymph!

Riodinid pupa (Brachyglenis sp.) mimicking the Vestria katydid nymph. Photo by Paul Bertner

From a blattodean to Nilio beetles

This is the story about how a small blattodean taught me something I did not know about beetles.

While photographing frogs in the Ecuadorian Amazon this past October, I noticed a tiny insect running across the surface of a fallen leaf resting on the forest floor. It had bright colors and looked interesting, so I collected it in hopes to photograph it later. When I finally got to do it, I was struck by its deception. You see, when I initially spotted it I thought it was a beetle. The dome-shaped body and the bright coloration resembled those of some leaf beetle species (family Chrysomelidae), and this insect even moved and walked like a beetle. Nevertheless, a close inspection revealed that its whole body was segmented. This was no beetle. It was a blattodean nymph.

Beetle-mimicking cockroach nymph

Beetle-mimicking cockroach nymph. What could be the model species?

Beetle-mimicking cockroach nymph

Blattodeans exhibit some beautiful examples for mimicry, with some species resembling poisonous fireflies and venomous assassin bugs. It should come as no surprise that a blattodean might benefit from looking like a leaf beetle. While many leaf beetles are harmless, some species harbor chemical compounds that make them poisonous or distasteful to predators. Unfortunately, identifying a blattodean from its larval stage is very tricky and close to impossible. I was not able to locate anything that looked like the adult stage of this species. However, when I examined this cute blattodean I remembered that I have seen this color scheme on a leaf beetle before, and after digging in my old photo archive I was able to find the record.

Leaf beetle. Or is it?

I took this photo on one of my first visits to Ecuador, over a decade ago. I did not plan to do anything with the photo, but I thought it was a nice-looking leaf beetle and so I snapped a quick photo for my own records. Only I was completely off. This is not a leaf beetle.

Unlike most of its family members that are elongated and dull-colored, Nilio is a genus of darkling beetles (family Tenebrionidae) that bear a striking resemblance to leaf beetles and ladybugs. This resemblance can fool even experienced entomologists. Darkling beetles are well-known for their chemical defense, secreting odorous chemicals that will deter even the most enthusiastic field entomologist. This can explain the blattodean mimicry shown above.

This is not a leaf beetle but a darkling beetle (Nilio sp.)

After I realized these photos show a species of Nilio, I checked the rest of my photos from the very same trip, and started finding more photos of Nilio species.

Darkling beetle larvae (Nilio sp.) feeding on lichens

Here is a group of larvae on a branch. Nilio larvae are gregarious (live in groups) and feed on epiphytic lichens. If you have ever seen the typical wire-worm larvae of darkling beetles you will understand why I labeled this photo as “chrysomelid larvae” in my archive.

Darkling beetles (Nilio sp.) aggregating next to pupation site

In some species, not only the larvae, but also the adults, are gregarious. Here is a group of adults I found on a tree trunk close to their pupation spot. Like the larvae, these adults were feeding on lichens as well.

A closer look at the Nilio beetles aggregation

As you can see, not all Nilio species have bright coloration as the species shown above. However, even when they are closer to their “darkling roots” they still look more like to members of Chrysomelidae than Tenebrionidae. This all goes to show that even when you are confident about your knowledge of insect taxonomy or biodiversity, nature can still surprise you. I embrace these moments when I am caught unprepared; nothing like learning something new!

This leaf got me thinking

I sometimes like to drift away in my thoughts and reflect on my days before becoming a biologist. It is amazing to realize how much I have learned over the years. This is something I think many people take for granted nowadays. We are flooded with easily accessible information on a daily basis. Try to think how many new things you learned just in the last month.
A little over a decade ago, I embarked on my first big overseas trip. Back then I knew close to nothing about Latin America. I had one goal in mind: to see poison dart frogs in the wild. Not too long into the trip I already felt victorious, after spotting some of these frogs in Bolivia and Ecuador. My quest took me to Costa Rica, where I found more of these stunning hopping jewels. Although I was mainly interested in amphibians, I was overwhelmed by the richness and diversity of arthropods. And more interestingly, despite my knowledge and exposure to various insect species, I realized how much I do not know and need to learn.

One such moment occurred when I visited the pastoral town of Monteverde, more specifically the butterfly gardens there. The guided tour I took passed near a moth wall, which was basically a white painted wall with a powerful light source pointing at it during nighttime. This was the first time I have ever seen a light trap. It was packed with hundreds of moth species. I was fascinated. The other visitors – not so much. They were pressing me to leave these “boring brown bugs” so we can head over to the butterflies area. “Just a second” I replied, “there is one moth I have to photograph”.

Leaf-mimicking moth, Monteverde, Costa Rica

Leaf-mimicking moth, from Monteverde, Costa Rica. Amazing camouflage, down to the level of leaf (=wing) damage and asymmetry. Image scanned from an old film slide.

“That’s not a moth” argued one of the visitors, “it’s just a fallen leaf that was blown onto the screen door”.
The local tour guide smiled but kept his silence.
“Well, if it is just a leaf…” I said and stood up, “…why don’t you touch it then?”
Upon being touched, the “leaf” immediately came into life and took off in a slow flight, disappearing into the foliage.

Many insects try to look like leaves. It is one of the most common types of crypsis. Only some of these insects, however, take it to the next level, mimicking not only the shape and color of leaves, but also their texture, tissue damage and even asymmetry. This moth had all of these. For years I have been waiting for an opportunity to photograph such a moth again, and finally, last year, I stumbled upon a similarly impressive species in the Amazon basin of Ecuador.

Leaf-mimicking saturniid moth (Homoeopteryx sumacensis), Amazon Basin, Ecuador

Leaf-mimicking saturniid moth (Homoeopteryx sumacensis) from the Amazon Basin, Ecuador. It was resting on the bathroom floor – I do not think I would be able to see it if it was resting among fallen leaves.

This species does look (and behave) very much like a leaf. Instead of laying flat like most moths, it holds its wings up in a way that creates a three-dimensional appearance. The forewing tips and margins are delicate; they are usually the first part to suffer tears and damage, contributing to the asymmetrical look of the false leaf. I knew immediately that I want to keep this photo for something special, and I decided to share it on the last day of National Moth Week. After posting it, the internet went wild. The photo was shared hundreds of times on social media, sparking discussions about evolution and moth diversity. It encouraged people to post their own photos of cryptic moths; others messaged me that the photo helped them to see the beauty and uniqueness of moths. I could not be happier.

From this angle it is easier to see that it is a moth. Leaf-mimicking saturniid moth (Homoeopteryx sumacensis)

It is important to remember though, that this moth is just one small example from a vast world of moths. There are over 150,000 species of moths worldwide, many undescribed, and many more waiting to be discovered. Moths are everywhere. There is more to them than meets the eye. They take many forms, and can sometimes make you doubt yourself. Until that moment in Costa Rica I was not aware these leaf moths existed, and even today I am not certain of their exact species ID*. Even nowadays within the highway of free information, I still have a lot to learn.

The positive feedback this photo received, as well as my orchid bees photo, made me realize also how much I am grateful for all the people who find my content interesting or inspiring. I never mention this, but it gives me a lot of energy. When things get rough, I remind myself that there is at least someone out there who thinks what I do is cool. I want to take this opportunity to thank all my followers, commenters and visitors. I got to know some fascinating people since I started posting. Thank you, everyone.

*UPDATE: This moth has been identified by Vazrick Nazari from the Canadian National Collections as Homoeopteryx sumacensis, a saturniid moth.

Ornidia – an orchid bee mimic

In my previous post I mentioned that one of the most common questions I got was whether orchid bees are some sort of fly. Indeed there are many flies that have metallic colors, but the resemblance usually stops there. The best example are bottle flies, members of family Calliphoridae, which occupy a niche different from that of orchid bees and do not share any similar behaviors with them. It does not mean, however, that Euglossinae-mimicking flies do not exist. In the tropics, some hoverflies (family Syrphidae) have evolved to look like orchid bees. Several species of the genus Copestylum resemble Euglossa species and they are often found foraging near active orchid bees. Even more interesting is Genus Ornidia, which bears a strong visual resemblance to some Euglossa species, and even copies some of the bees behavior.

Orchid bee-mimicking hoverfly (Ornidia obesa) feeding, Amazon Basin, Ecuador

The genus Ornidia contains five species, all have shiny metallic colors and body structure that resemble those of orchid bees. Their legs in particular are thick and robust to look more like bee-legs than the typical skinny legs of hoverflies. Ornidia are distributed mainly in the tropical regions of Latin America, however one species, Ornidia obesa, reaches the southern United States and has also spread into the Afrotropical, Oriental regions and Oceania, probably due to human activity. Ornidia flies are quite common and they are frequently found close to human habitations.

Despite having hairs covering their body, Ornidia flies are extremely shiny, almost like small mirrors.

These beautiful flies can be observed safely even from a close distance. They are not very skittish, and usually when disturbed they quickly take off, hover in the area for a few seconds, and return to the same perch. It is especially rewarding to watch them warming up during the morning hours, when they hover in a single spot for a while, trying to catch some sun rays penetrating through the canopy. The loud buzzing sound produced by their wings during flight is very similar to that of Euglossa species. During flight, the fly also displays a behavior that appears to mimic orchid bee behavior: it crosses its legs several times, similarly to a male Euglossa transferring fragrant compounds to the hind tibiae, or alternatively to a female Euglossa transferring resin to the hind legs.

Closeup on the head of Ornidia obesa. The clypeus area (front of head) is exceptionally beautiful and mimics Euglossa’s clypeus quite faithfully.

The adult flies feed mainly on liquid food such as nectar and animal feces, but can also take small-sized particles like pollen and fragments of decomposing organic matter. Ornidia larvae are generalist feeders and seem to exploit various food sources to complete their development. Firstly, they can be found in rotting fruits, leaf litter and compost piles. Several interesting papers report the larvae to feed even on vertebrate corpses, suggesting the potential use of these maggots for forensic work. Lastly, Ornidia larvae were also found to cause intestinal myiasis in humans, after being ingested with infested food. Nevertheless, these flies pose no threat to us; Myiasis caused by Ornidia larvae is rare relatively to other fly species, the flies have plenty of abundant food in their habitat and there are no records of Ornidia flies completing their development inside a human host.

Copestylum viridis is a small species of hoverfly that, like Ornidia obesa, mimics Euglossa bees. This species is often seen feeding near active orchid bees. Photographed in the Amazon Basin, Ecuador

How would a fly benefit from looking like an orchid bee? As I mentioned in my post about Euglossinae, these bees are not very aggressive due to their solitary lifestyle. However, the flies may still benefit from this mimicry because the bees are dominant in the rainforest habitat. The female orchid bees have a stinger and can deliver a painful sting, this alone can deter a predator. In addition, the highly territorial male orchid bees are usually left alone by other flying insects. The mimicking flies take advantage of the fact that orchid bees are common and recognized by other animals, including predators.

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