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What butterflies like

In Eastern Cape of South Africa, a beautiful flock of butterflies is puddling on the side of a road. [Canon 7D, Canon 16-35mm]

In Eastern Cape of South Africa, a beautiful flock of butterflies is puddling on the side of a road. [Canon 7D, Canon 16-35mm]

The weather has become so unpleasantly cold that I try not to open my eyes while walking outside, out of fear that my eyeballs will freeze. (I was told that this would happen by my teacher in preschool; she also told me that eating candies makes worms lay eggs in my teeth, and that if I eat pears before swimming then I will drown. Why pears and not, let’s say, gooseberries, I have no idea, and I won’t even mention what she said would happen if I ran with scissors.) Anywho, the lifeless season outside the window makes me seek solace in memories of warmer places, luxuriantly abundant with life, and few phenomena better convey the feeling of life’s unbound exuberance than swarms of tropical butterflies.

A cluster of puddling butterflies on a sandy river bank in Guyana [Canon 5D, Canon 100-400mm]

A cluster of puddling butterflies on a sandy river bank in Guyana [Canon 5D, Canon 100-400mm]

Visitors to the tropics are often surprised by the number of butterflies and moths aggregating on muddy banks of rivers, mud puddles and, this usually comes as a surprise, animal dung. Many butterflies are also attracted to human skin and suck sweat or blood from cuts with their proboscis. They love wet, sweaty socks and shoes, and absolutely adore the stuff that seeps out latrines. We may delude ourselves that all butterflies prefer sweet nectar of flowers, but in fact many would rather gorge on the liquid portion of fresh feces.

African veined white (Belenois gidica) extracting minerals from wet sand (Eastern Cape, S. Africa) [Canon 7D, Canon 100mm macro]

African veined white (Belenois gidica) extracting minerals from wet sand (Eastern Cape, S. Africa) [Canon 7D, Canon 100mm macro]

This behavior, known as puddling, is decidedly more common among male than female butterflies. A series of studies has demonstrated that the main element these insects are after is sodium. Sodium is difficult to find in plant material consumed by the butterfly larvae, although potassium occurs there in abundance. By sucking fluids rich in sodium, adult butterflies try to replace the surplus of the latter element with the former. In extreme cases a moth may imbibe an amount of fluid 600 times its own weight in a single puddling session, expelling the excess water as it drinks and retaining only the precious mineral. It has been shown that a higher sodium content in the male’s body enhances his mating success i.e., fitness. In addition to sodium, moths and butterflies may extract amino acids from soil and animal excrements, and males of some species transfer these compounds to their partners through a spermatophore during mating, thus investing in their offspring.

Puddling butterflies turned out to be remarkably skittish – in order to get a wide angle shot of these insects I had to leave the camera in the sand, and use a radio controlled trigger (seen on the left) to get the shots. [Canon 5D, Canon 100-400mm]

Puddling butterflies turned out to be remarkably skittish – in order to get a wide angle shot of these insects I had to leave the camera in the sand, and use a radio controlled trigger (seen on the left) to get the shots. [Canon 5D, Canon 100-400mm]

While in Guyana a few years ago I noticed a particularly large aggregation of butterflies on the sandy bank of a small river that was lazily flowing near our camp. The patch of sand that the insects were obsessing about didn’t look any different from the rest of the beach, but there had to be something in it that made the butterflies go crazy. I had my suspicions as to what was in the sand, but decided to find out for sure. Alas, after many hours spent crawling around, watching and photographing the butterflies, the reason for their strange behavior was still a mystery. But the following night, as I quietly crept through the forest searching for katydids, I suddenly heard the unmistakable sound of water gushing from a faucet. As quietly as I could I moved closer to the river, and there it was – a huge tapir, taking a leak on the patch of sand where the butterflies loved to aggregate, and where I had just wallowed in for hours. My consolation is that the sodium and amino acids that I surely must have absorbed through my skin might increase my fitness as well.

This large aggregation of butterflies puddling in Guyana is probably made up mostly of male individuals. [Canon 1Ds MkII, Canon 16-35mm]

This large aggregation of butterflies puddling in Guyana is probably made up mostly of male individuals. [Canon 1Ds MkII, Canon 16-35mm]

To some butterflies, residues of my sweat were more tempting than the stuff in the sand (tapir – 0, me – 1) [Canon 5D, Canon 100-400mm]

To some butterflies, residues of my sweat were more tempting than the stuff in the sand (tapir – 0, me – 1) [Canon 5D, Canon 100-400mm]

The best spots to see large aggregations of tropical butterflies are often places visited by large grazers. Their dung often attracts many different species of insects seeking sodium and amino acids. [Canon 7D, Canon 16-35mm]

The best spots to see large aggregations of tropical butterflies are often places visited by large grazers. Their dung often attracts many different species of insects seeking sodium and amino acids. [Canon 7D, Canon 16-35mm]

The most interesting find of 2012

Caterpillar of Paraclystis integer, a termite inquiline from Mozambique (lateral and dorsal views) [Canon 7D, Canon 100mm macro, 3 speedlights Canon 580EXII]

Caterpillar of Paraclystis integer, a termite inquiline from Mozambique (lateral and dorsal views) [Canon 7D, Canon 100mm macro, 3 speedlights Canon 580EXII]

Well, the first year of my blogging is nearly over, but I think I still have time for one more story. And it is a good one.

Earlier this year I was in the spectacular Gorongosa National Park in Mozambique, doing my usual things – chasing katydids with a net and a recorder, taking pictures, and flipping rocks. And under one of these rocks I found something that truly tested the extent of my entomological knowledge. One evening, while looking for ants and crickets on the rim of a deep limestone gorge, I lifted a big, flat boulder and underneath found a colony of termites. But something wasn’t right. Why were some of these termites longer? And wierd looking? It took me a few seconds to realize that the colony was filled with creatures that looked very much like termites, and behaved in a similar fashion, but clearly were something else.

A fragment of the carton structure of the Schedorhinotermes lamanianus colony with termite soldiers and caterpillars of Paraclystis integer [Canon 7D, Canon 100mm macro, 3 speedlights Canon 580EXII]

A fragment of the carton structure of the Schedorhinotermes lamanianus colony with termite soldiers and caterpillars of Paraclystis integer [Canon 7D, Canon 100mm macro, 3 speedlights Canon 580EXII]

At first I couldn’t even guess what these creatures were. Mutant termites, an undescribed phylum, aliens? There were hundreds of them, easily as many as the real termites. I scooped a bunch into a container to have a closer look. OK, they were not aliens – they had mandibles and six short legs. So they were insects. But what kind? I had no idea.
Later I examined them under a microscope and saw that they had crocheted prolegs on the abdomen – so they must be caterpillars, that is moth or butterfly larvae. But they also had strange processes all along the body that looked strangely similar to candy-corn. The peculiar caterpillars turned out to be Paraclystis integer, members of the cloth-moth family (Tineidae). But what were they doing in the termite colony?

Although these caterpillars and their presence in the colonies of the termites of the genus Schedorhinotermes have been known since early 1900’s nobody really knows what the nature of the relationship between these two groups of insects is. It is tempting to speculate that the caterpillars’ strange candy-corn processes produce something that the termites like, but this is not the cases. They appear to be purely of a sensory nature and are not connected to any glands. Even more strangely, the caterpillars seem to have little tolerance for termites, and often chase them away if approached. At times, however, they allow termites to lick something from the dorsal part of their abdomen. There is one casual observation made in the late 1960’s (Harris 1968. Proc. R. ent. Soc. Lond B. 37: 103-113) suggesting that the larvae accompany the termites on their foraging trips at night, but what exactly they feed on is unknown.

I am hoping that in 2013 the mystery of the candy-corn caterpillars and termites will be one I am able to solve. And if I do, you will be first to learn about it on The Smaller Majority blog. Thanks for reading and a Happy New Year!

What happens on the fourth Thursday of November

Winter moths on my kitchen window, a sure sign that Thanksgiving is near. [Canon 7D, Canon 24-105mm]

The fourth Thursday of November is upon us, and this can mean only one thing – winter moths are coming! A few days ago, while trying to decide if this year we should have a turkey or two turkeys for dinner, Kristin looked up from the menu list she was working on and said, “Thanksgiving moths should be here soon.” I never realized it, but this is a much more appropriate name for these insects, members of the family Geometridae, which begin to flutter around the lights of our house around this time of year. Sure enough, that very night the first Winter moth (Operophtera brumata) came to the light of the kitchen window, and their numbers have been picking up since.

Winter moths are interesting animals. Unlike most species of moths and butterflies, they are strongly sexually dimorphic. In fact, while the male looks like your typical, grayish-brown geometrid moth, you will be hard pressed to recognize the female as a member of the same order of insects. She is plump and flightless, with wings reduced to tiny lobes that often resemble tufts of hair. Her mouthparts are reduced (not much to feed on for a moth at the end of November), and the only clue that she is in fact a moth comes from the scales that cover her entire body.

A caterpillar and adults of the Winter Moth (Operophtera brumata). [Canon 7D, Canon 100mm macro, 3 speedlights Canon 580EXII]

In the coming days we will be seeing more and more mating pairs, until the arrival of permanent freezing weather kills them all off. But their eggs, safely hidden in the bark of maples that grow around our house, will hatch next spring, and thousands upon thousands of small, green caterpillars will commence their prodigious pooping on our deck at the end of April. Some years there are so many of them that the foliage of our maples is almost completely gone by the end of May. The incredible abundance of this moth is a clue to the fact that this species does not really belong here. It is an invasive species that arrived from Europe in the 1930’s, and has since spread across the entire North American continent. And because it does not have too many natural enemies here, it is able to breed in numbers higher than those of many native moths. A closely related, native species, O. bruceata, is rarely seen in similarly high densities.

Female Winter Moth (O. brumata) on the tree trunk of a maple tree in front of our house. [Canon 7D, Canon 100mm macro, speedlight Canon 580EXII]

Winter moths (Operophtera) are not the only moths that come out around this time, and also not the only ones with remarkable morphological differences between males and females. I found another geometrid moth, the Fall Cankerworm Moth (Alsophila pometaria), yesterday on a tree trunk in Estabrook Woods. These animals are even stranger, with females completely devoid of any traces of wings, and resembling a velvet sausage running on long spindly legs.

Although winter moths are not the only insects active at this time of year, and some insects remain active even during freezing weather, their appearance reminds me of two things. First, that the insect season is truly over, and they are the last things to come to the lights of our house until spring. And second, that this Thursday night I will assume the appearance of a winter moth female, stuffed to the breaking point like a sausage, and definitely incapable of flying.

Female Fall Cankerworm Moth (Alsophila pometaria) from Estabrook Woods, MA. [Canon 7D, Canon MP-E 65mm, 3 speedlights Canon 580EXII]

The Mystery of Flying Honeydew

Lantern bug (Enchophora sanguinea) expelling a jet of honeydew droplets [Canon 1Ds MkII, Canon 100mm macro, 2 speedlights Canon 580EX]

Although my entomological interests focus on katydids and other orthopteroid insects, a few years ago I started paying a closer attention to lantern bugs (family Fulgoridae), large insects remotely related to cicadas, which feed on plant nutrients that flow inside tree trunks. Lantern bugs have very long, stiletto-like mouthparts, which allow them to pierce the bark and tap into a rich stream of juices in the plant’s vascular tissue known as the phloem. This liquid is exceptionally rich in sugars, but it also contains small quantities of proteins and minerals, and it is mostly the last two that the insects are interested in. Consequently, lantern bugs end up with a huge surplus of water and carbohydrates in their diet, which they need to get rid off, and they do so by producing copious amounts of a sugary liquid known as honeydew. Other insects, such as aphids and scale insects, also produce honeydew, and they expel it slowly, in large droplets that accumulate at the tip of their abdomen. This makes it easy for other animals, ants especially, to come and lick it off – after all it would be a shame if all this sugar went to waste. Often, in return for the sweet treat, ants defend their “cattle” from predators.

Two species of blattodeans (Eurycotis spp.) collecting honeydew from the same lantern bug individual [Nikon D1x, Sigma 180mm, flash Nikon SB-28DX]

But until recently a similar relationship was not known to occur between lantern bugs and other animals. The reason was simple – unlike aphids, which produce a slow, easy to collect stream of honeydew, lantern bugs shoot honeydew out of the abdomen as a jet of tiny droplets that fall a great distance away from their bodies. I was able to measure the speed with which the honeydew was expelled by these insects, and it turned out to be between 0.8 and 1.7 m/sec (2.6-5.6 ft/sec.) No animal, it seemed, was capable of tapping into this nutritious but elusive resource – imagine trying catching beer cans flying with the speed of 60 miles/hour (if we adjust for differences in size and taste preferences.)

Moth (Euclystis proba) with a freshly caught droplet of honeydew on its proboscis. [Canon 10D, Canon 100mm macro, MT-24EX twin light]

Now we know, however, that the story is far more interesting. Together with my friend Kenji Nishida, a great Japanese entomologist and photographer, we have discovered that there exists an entire suite of organisms with unique behaviors that allow them to collect lantern bugs’ honeydew. We did our work in Costa Rica, primarily in the lowland to mid-elevation rainforest of the Atlantic part of the country. We discovered that there was a number of species of blattodeans (fascinating cousins of praying mantids and termites), who tapped the abdomen of lantern bugs with their front legs or maxillary pals, and were rewarded with a stream of honeydew that went directly into their mouths. The most astonishing part of this behavior was that occasionally we would see two or three blattodeans of different species forming a line behind a single lantern bug, patiently waiting for their turn! This unexpected politeness makes a lot of sense: a commotion of large insects fighting for access to a lantern bug would very likely spook the shy and skittish animal, and in the end nobody would get anything.

Lantern bug with two simultaneous moth guests (small Platynota sp. and larger Elaeognatha argyritis) [Canon 10D, Canon 100mm macro, MT-24EX twin light]

We documented a similar behavior in several species of moths, another group of frequent visitors to lantern bugs. The moths were able to catch individual, flying droplets of honeydew with their long proboscis and, like the blattodeans, sometimes formed a well-mannered line behind the insect.

Every now and then we would see a lonely ant looking wistfully at a lantern bug, but ants are simply too small to be able to catch the fast-flying honeydew, and never did we witness them being able to feed directly on the jet of honeydew droplets. We assumed that this bountiful source of sweet pee was forever beyond their reach. As it turned out, we were wrong. But to find out how ants manage to get the lantern bugs’ honeydew you will need to tune in tomorrow for the exciting conclusion of “The Mystery of Flying Honeydew!”

Update: Read the conclusion of the mystery.

Devil’s got a pretty face

A portrait of a limacodid caterpillar from Cambodia [Canon 1D MkII, Canon MP-E65mm macro, Canon MT-24EX twin light + Canon 580EX speedlight]

Many things have bitten, pinched, stung, or jabbed me over the years, but the absolute champions in delivering the most memorable, painful experience are pretty little insects known as the slug caterpillars. They are larvae of equally handsome moths, members of the family Limacodidae.

The body of most limacodid caterpillars is covered with long, brittle spines, which break off easily and lodge into the skin of anybody foolish or unlucky enough to get in contact with them. Each spine is connected to a small venom gland and is filled with a mix of compounds, among them histamines and formic acid. These toxins tap right into our nociceptors (pain receptors), and produce immediate sharp pain, followed by swelling or rash. Not surprisingly, these insects have few natural enemies, and those that attack them do so by being able to hit them between the spines, and thus avoid being stung.

Many species of limacodids advertise their unpleasant properties with beautiful, striking colors, employing the principle that is known to every bird and lizard, but one that we humans often forget: if it’s pretty, it’s gonna hurt you. But I knew that when I was photographing a cluster of threateningly black and yellow slug caterpillars in a rainforest of Suriname, and was very careful not to brush against them. It all went very well, that is until I got a little too close and the liana on which they were sitting snapped back, and all of them smacked against the palm of my hand. My screams were apparently heard half a mile away, and I had no use of my arm for the next 24 hours.

Adult limacodid moths lack any formidable defenses, and instead rely on crypsis, blending into their surroundings. Some, like Costa Rican Perola producta, are difficult to identify at first sight as moths even by seasoned entomologists.

Some limacodid caterpillars, like these Acharia sp. from Suriname, cluster together to enhance their warning message [Canon 7D, Sigma 15mm EX DG Diagonal Fisheye, Canon MT-24EX twin light]

Adult limacodid moth (Perola producta) from Costa Rica) [Canon 1Ds MkII, Canon 180mm macro, two Canon 580EX speedlights]