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Mozambique Diary: Red-headed flies

Red-headed flies (Bromophila caffra) are striking and common animals in East and southern Africa, but little is known about their biology.

Red-headed flies (Bromophila caffra) are striking and common animals in East and southern Africa, but little is known about their biology.

Two months, that’s how long I have been neglecting this blog. Some people had even sent me messages to check if I were still alive. But I am alive and the reasons for my silence were good – until last week I was in Mozambique, working at the Wilson Lab and busily preparing for the next biodiversity survey of Gorongosa National Park. While there I had precious little time to write or take photos, but I did manage to take some shots of a few interesting critters. It is the rainy season in Gorongosa now and insect life is exploding. I had set up an ultraviolet light in front of my office to collect all members of my target groups (orthopteroid and dictyopteroid insects) and to cherry-pick the more interesting species from orders that we don’t yet collect systematically. On some nights the sheet was sagging under the weight of hundreds of species of insects and for a while mysterious redheads kept coming to the light.

Red-headed flies, which in Mozambique emerge at the end of the rainy season, like to hang in clusters on leaves.

Red-headed flies, which in Mozambique emerge at the end of the rainy season, like to hang in clusters on leaves.

I recognized them from my earlier trips to Gorongosa as Red-headed flies (Bromophila caffra) – large, slow moving insects, reluctant to take to the air, and much happier to hang in clusters from low tree branches. They are truly striking animals, showy and clearly unconcerned about attracting anybody’s attention, including that of potential predators. There were many birds and grabby vervet monkeys in the camp, who not so much as looked in the direction of the flies who slowly spun in clusters on leaves.

Adult Red-headed flies feed on dung and other decaying organic matter.

Adult Red-headed flies feed on dung and other decaying organic matter.

But for an insect as conspicuous and common as the Red-headed fly, shockingly little is known about its biology. In fact, the last scientific paper that mentions it by name (according to an extensive MetaLib cross-database search) is from 1915, and it does so only to compare the fly’s strikingly red head to another species. As already pointed out in an excellent post about this species by Ted C. MacRae, there exists only anecdotal evidence that the larvae of this species might be feeding on the roots of Terminalia trees, potentially sequestering toxic cyclic triterpenes, which would explain the adult flies’ aposematic coloration. But, as is the case with so many African invertebrates, nobody really knows.

There is also another possibility. One morning while in Gorongosa I woke up to find my arms covered with big, painful blisters. The night before I had spent a couple of hours searching for insects in tall grass and remembered seeing many contrastingly colored, red and black beetles of the genus Mylabris. “Oh, that’s why they are called blister beetles!”, it dawned on me, a little too late. While walking through the grass I must have brushed against some of these insects, and a mere touch against my skin caused the blisters, which lasted for over a week, to appear. The beetles themselves are highly toxic, deadly even, and no bird or other vertebrate will try to eat them. It is therefore quite possible that the flies are fakers – not toxic at all but simply counting on predators’ reluctance to try a potentially harmful meal. This phenomenon, known as Batesian mimicry, is common in the animal kingdom and I strongly suspect that the flies are an example of it.

I strongly suspect that Red-headed flies are Batesian mimics of blister beetles of the genus Mylabris. These beetles not only cause painful, long-lasting blisters but are also potentially deadly toxic.

I strongly suspect that Red-headed flies are Batesian mimics of blister beetles of the genus Mylabris. These beetles not only cause painful, long-lasting blisters but are also potentially deadly toxic.

When I return to Gorongosa next month the flies should still be around. It will also be the time when many young house geckos (Hemidactylus mabouia) are hanging around the lights of the camp, having hatched in January and February. It might be a bit evil on my part, but I think I will do some feeding experiments to see if the lizards, which at that point should still be naive about the flies, have any adverse reaction to eating them. Watch this space.

One peculiar morphological characteristic of the Red-headed flies is the absence of the ocelli, which are typically found on the head of other flies.

One peculiar morphological characteristic of the Red-headed flies is the absence of the ocelli, which are typically found on the head of other flies.

Dermatobia Redux

Raising two dipteran children was an interesting experience. It was embarrassing on a few occasions, when both of my arms started bleeding profusely in public; painful at times, to the point of waking me up in the middle of the night; and inconvenient during the last stages of the flies’ development, when I had to tape plastic containers to my arms to make sure that I will not lose the emerging larvae. But other than those minor discomforts it was really not a big deal. Perhaps my opinion would have been different had the bot flies decided to develop in my eyelids, but I actually grew to like my little guests, and watched their growth with the same mix of pleasure and apprehension as when I watch the development of any other interesting organism under my care.

Having two bot fly larvae embedded in my skin have also made me ponder once again the perplexing element of the human psyche that makes us abhor parasites but revere predators. Why is it that an animal that is actively trying to kill us, such as a lion, gets more respect than one that is only trying to nibble on us a little, without causing much harm? I strongly suspect that it has to do with our genetically encoded sense of “fairness” – we perceive parasites as sneaky and underhanded, whereas predators attack us head-on and thus expose themselves to our retaliation. They are brave, or so we think. This, of course, is a very naive and anthropomorphic interpretation of nature. A lion is no “braver” than a bot fly, who has to skillfully hunt mosquitos to assure the dispersal of her eggs and risk more dangers than a lion, a top predator with no natural enemies. Most importantly, to a bot fly we, humans, are a renewable resource – it is in the bot fly’s best interest that we live a very long life and thus can be “reused” – hence the minimum amount of suffering that this species causes. To a lion we are nothing more than a one-time meal. But we should not judge either species for their actions – there is no “good” or “bad” in nature – nature is amoral.

I am saying this to prepare you for a short video that I have made about my experience of raising a bot fly. I don’t want you to think that it is “creepy” or “weird”. It is simply a documentation of an interesting organism, who happens to develop in the skin of large mammals. But please be forewarned that this video includes a few sequences that some viewers may find disturbing. If you don’t want to have nightmares about things living inside you (which they already do, by the way), please don’t watch it. But if you are prepared to be open-minded and appreciate God’s wonderful creations in all their amazing glory, enjoy the show!

So long, 2014

It was an interesting, busy year, which explains in part why I have been neglecting this blog recently. I am not going to give a month-by-month account of 2014 but thought that a few highlights might be in order.

Early in the year I made a brief visit to Quirimbas National Park in northern Mozambique where I found Pardalota karschiana, one of the most remarkable and beautiful katydids in the world.

Early in the year I made a brief visit to Quirimbas National Park in northern Mozambique where I found Pardalota karschiana, one of the most remarkable and beautiful katydids in the world.

The most important event of 2014 for me was, unquestionably, the opening of the E.O. Wilson Biodiversity Laboratory in Gorongosa. This facility, which I now direct, is quickly becoming a hub of renewed scientific and educational activity in Mozambique. Here our technician Ricardo Guta teaching kids from nearby schools about insects of Gorongosa.

The most important event of 2014 for me was, unquestionably, the opening of the E.O. Wilson Biodiversity Laboratory in Gorongosa. This facility, which I now direct, is quickly becoming a hub of renewed scientific and educational activity in Mozambique. Here our technician Ricardo Guta is teaching kids from nearby schools about insects of Gorongosa.

I have my first encounter with the African lungfish. This animal appears to be more resourceful than I ever suspected. Here a PBS cameraman John Benam and producer James Byrne witness its amazing ability to escape.

I have my first encounter with the African lungfish. This animal appears to be more resourceful than I ever suspected. Here a PBS cameraman John Benam and producer James Byrne witness its amazing ability to escape.

In April E.O. Wilson and I published a book on the biodiversity of Gorongosa and the efforts to restore this unique place on Earth.

In April E.O. Wilson and I published “A Window on Eternity“, a book on the biodiversity of Gorongosa and the efforts to restore this unique place on Earth.

During a BugShot macrophotography workshop on Sapelo Island in Georgia I find my first zorapteran!

During a BugShot macrophotography workshop on Sapelo Island in Georgia I find my first zorapteran!

Back in Gorongosa, with the help our mammalogist Jen Guyton, I learn how to shoot bats in flight.

Back in Gorongosa, with the help of our mammalogist Jen Guyton, I learn how to shoot bats in flight.

A short trip to Belize in September gives me a chance to meet Uo, the mythical rain caller.

A short trip to Belize in September gives me a chance to meet Uo, the mythical rain caller.

A successful sting operation leads to the rescue of a pangolin and her baby from a poacher – I finally get to see and touch the animal I had been dreaming of seeing all my life.

A successful sting operation leads to the rescue of a pangolin and her baby from a poacher – I finally get to see and touch the animal I had been dreaming of seeing all my life.

The internets go batshit crazy over a single specimen of a common arthropod collected for scientific research.

The internets go batshit crazy over a single specimen of a common arthropod collected for scientific research.

That’s about it – I am looking forward to 2015, which promises to be even more exciting. Watch this space and thank you for reading!

What to do?

This morning, in my bathroom, I was faced with a dilemma.

Spider_in_sink

And here are the results of the poll on what I should do about this sticky situation. It is heartening to see that the majority of voters would release the spider (which is what I did), but also rather sad that over 38% of respondents (discounting the 5% who were high while voting) would resort to violence (against either me or the spider). Votes

Mozambique Diary: Webspinners

An adult female of a yet unidentified webspinner from Gorongosa National Park.

An adult female of a yet unidentified webspinner from Gorongosa National Park.

It has been a busy couple of months for me – first organizing a month-long biodiversity survey in Gorongosa National Park, then dealing with various aspects of our newly created E.O. Wilson Biodiversity Laboratory. But now that I am home I can process all the photos taken in Mozambique and, finally, write a few long overdue blog posts.

Our second biodiversity survey of the park started with a week of sampling in the Sand Forest, an interesting plant community near Chitengo, the park’s main camp. While somewhat underwhelming at first glance, this stunted forest that grows on remarkably infertile, pale and sandy soils, produced some of the finest discoveries of the survey. It was also an exciting place to be, on the account of roaming elephants (who really didn’t like people invading their private feeding ground) and a radio-collared male lion (who, I was told by our lion researcher Paola Bouley, might actually “like” people).

Males of many webspinner, such as this cosmotropical Oligotoma saundersii, are fully winged. Their wings can easily flex in half over the top of the body to help them move backward in the narrow silky corridors.

Males of many webspinner, such as this cosmotropical Oligotoma saundersii, are fully winged. Their wings can easily flex in half over the top of the body to help them move backward in the narrow silky corridors.

The first thing that I noticed was that many tree trunks in the forest were covered with extensive carpets of silk. This was great because for the last two years I had been searching in Gorongosa for the elusive webspinners (Embiidina), an order of semi-social insects that build intricate silk corridors on trees and rocks. No species of webspinners has ever been recorded from Mozambique but I knew that they had to be there. To be precise, I did find a webspinner once in Gorongosa, but it was an introduced, Asian species Oligotoma saundersii, which has a nearly cosmotropical distribution. But the animals on the trees of the sand forest were clearly something very different.  For one, they were huge. I am used to webspinners being tiny, brownish insects that you look for with a magnifying glass. But one adult female that we collected was pitch black and nearly 25 mm long, which probably makes her the largest webspinner in the world (the largest webspinner that I could find a record of is the South American Clothoda, which grows to 20 mm.) But despite their size these insects were not easy to find. I ripped through dozens of their silky colonies but found only a handful of specimens. Only later did I realize that during the day these insects were hiding deep in the crevices at the base of the tree or in debris-filled nooks between branches.

The thin sheet of silk acts as an invisibility cloak, protecting foraging webspiners from their principal enemies, ants.

The thin sheet of silk acts as an invisibility cloak, protecting foraging webspiners from their principal enemies, ants.

Webspinners have fascinated me for a long time. They are one of those animal groups that don’t attract much attention because of their small size and unassuming physique but, once you learn about their biology, they become very hard to ignore. The webspinners’ most obvious claim to fame is their ability to spin silk. But how do they do it? Spiders spin silk from spinnerets located at the tip of their abdomen (opisthosoma), but all insects (caterpillars, ant larvae, gryllacridid crickets, to name a few) have them located on their mouthparts. Or so the entomologists thought. And so strong was this conviction that early morphological descriptions of webspinners included silk-producing tubercles on the labrum which, upon closer inspection, turned out to be purely imaginary – as it happens, webspinners possess unique silk-producing, glands on their front tarsi, and not on their mouths. This explains their characteristic behavior of constantly waving the front legs – they are spinning silk, but the individual strands as so microscopically thin as to be completely invisible to the human eye. Only once hundreds or thousands of individual strands have been spun together do they begin to appear as a thin sheet of soft silk. The proteins that make up the spider and moth silk are some of the strongest organic compounds, resistant to breaking and very flexible. In contrast, the webspinners’ silk is remarkably weak and tears quite easily. This may have to do with its primary function – rather than being used to capture prey or protect a fragile developing pupa, it is merely a cloaking device that makes the insects invisible to ants while the webspinners graze lichens that cover bark or rocks. I have watched ants walk right on top of webspinners separated only by a diaphanous sheet of silk, while the webspinners were happily grazing on lichens, completely unperturbed by the presence of their deadly enemies.

The second function of the silk is the protection of eggs, which the female covers with silk and guards them until they hatch. She stays with the eggs mostly to chase away parasitoid scelionid wasps and plokiophilid bugs, and her presence increases the survival of eggs by 50%. But once the eggs are about to hatch the mother must remove the silk, otherwise the nymphs will not be able to emerge. She then stays with her children until they are ready to fend for themselves, initially masticating their food and spinning the silk corridors. She then leaves to start another colony.

The front tarsi of webspinners are strongly enlarged to accommodate silk-producing glands.

The front tarsi of webspinners are strongly enlarged to accommodate silk-producing glands.

Interestingly, some webspinners are the only social insects that are inquilines within the societies of other social animals – two species of Oligotoma from India build their societies inside colonies of a social spider Stegodyphus sarasinorum (but continue to spin their own silk). Another, Oligotoma termitophila, lives in termite colonies in Sudan.

So, what’s next for my Mozambican webspinners? Next time I am in Gorongosa I plan to look into their biology, and figure out what their colony structure and dispersal patterns are. The species also needs to be identified and described, which I should be able to do once I bring the specimens back from Mozambique (we hit a little snag with the export permits). I also plan to look for other species on Mt. Gorongosa. Who knows, I may also be able to find the webspinners’ closest relatives, the amazing zorapterans.

Silken galleries of webspinners covering trees in the Sand Forest of Gorongosa.

Silken galleries of webspinners covering trees in the Sand Forest of Gorongosa.

My life is now complete

A wingless form of zorapteran (Zorotypus hubbardi) from Sapelo Island, GA

A wingless form of zorapteran (Zorotypus hubbardi) from Sapelo Island, GA

When I set off for a long weekend on Sapelo Island in Georgia to teach insect photography at the BugShot workshop, it never occurred to me that the trip would culminate in completing a life-long quest. I am not one to keep bucket lists of things to see or do but, as an entomologist, I always hoped to personally collect all extant orders of insects. The most conservative classifications list about 28 orders of these animals, while others divide the class into more ordinal taxa (for example, Vitaly M. Dirsh divided the Orthoptera into 14 separate orders; thankfully nobody paid any attention to such craziness.) Regardless of the semantics, over the years I have collected all major lineages of insects, including such rarities as the Mantophasmatodea (in fact, I collected the second live specimen ever found; the first one was collected by Namibian entomologist John Irish about 10 minutes earlier), Grylloblattodea, or Strepsiptera. But one group has consistently eluded my grabby hands – the Zoraptera.

Warm, humid, and festooned with Spanish moss, the oak forest of Sapelo Island, GA, is an ideal habitat for the Zoraptera.

Warm, humid, and festooned with Spanish moss, the oak forest of Sapelo Island, GA, is an ideal habitat for the Zoraptera.

Described in 1913 by Italian entomologist Filippo Silvestri, Zoraptera are the least diverse order of insects – only 39 species are known, all in the genus Zorotypus (Mantophasmatodea have fewer species, but are divided into multiple genera and families.) As far as rare insects go, Zoraptera may appear somewhat underwhelming in their size and morphology – most species are only about 3 mm long, usually pale yellow or brown, blind and wingless. Their preferred habitat is also not very sexy as Zoraptera are found mostly in rotten logs across tropical and subtropical parts of the world, feeding on fungal hyphae or springtails. They are rather picky in their selection of habitat, and will only survive in logs that have reached the “Zorapteran stage” of decomposition – nothing more, nothing less (the five-stage classification of log decay was introduced in 1959 by E.O. Wilson, who to this day considers himself a zorapteran aficionado). Looking for Zoraptera is akin to looking for a grain of salt in a sugar bowl – in a log teaming with ants, termites and springtails you need to be able to spot a nearly microscopic, whitish insect that runs frantically in all directions, whose body proportions are only slightly different from those of a newly hatched termite nymph. It took me several hours of ripping through decaying logs and enduring countless stings of trap-jawed ants (Odontomachus) before I noticed an eensy dot of an insect that looked a little different. Even as I was putting it in a vial I was not quite sure that it was really a zorapteran, but my suspicion was confirmed the moment I looked at it through the macro lens of my camera.

Most zorapterans are pale, wingless and blind. Winged forms only appear if the decaying long in which they live can no longer support the population of these insects.

Most zorapterans are pale, wingless and blind. Winged forms only appear if the decaying log in which they live can no longer support the population of these insects.

But of course one should not judge the Zoraptera by their unassuming demeanor, for their behavior and reproductive biology are some of the most interesting among all insects. First, despite their name (zor [Gr.]=pure, aptera=wingless), winged forms are found in all species, albeit they only appear when the time comes to leave the log when it shifts from the “Zorapteran” to “Passalid stage” of putrefaction. And, once a new, nicely rotten habitat is found, the wings fall off. This type of behavior is not unique to the Zoraptera (aphids display a similar wing polymorphism), but what happens next is.

Zoraptera are not truly social, but often live in groups of 30+ individuals of various ages. But, unlike termites and ants, all individuals in the colony can reproduce, at least in theory. The colony is strictly patriarchal – the dominant individual is always the oldest male who maintains a harem of females and fights off younger males. Only when the senility kicks in, younger males have a chance to take over the top spot. This type of a male-dominated society is unique among arthropods, where it is always the females who control both reproduction and individual status in the colony.

Even more interesting is the way males inseminate the females. All across the animal kingdom males tend to be rather generous with the dispensation of their reproductive cells (to put it mildly), while females are frugal with their eggs, and choosy when it comes to mating. But in Zoraptera things are different – to inseminate the female the male produces only one (one!) sperm cell. And not just any sperm – the zorapteran spermatozoa are about 3 mm long, which, if you recall, is the average body length of the entire animal. Not surprisingly, males of these insects are not particularly eager to mate and it is the female who does most of the courting. Why this happens is not entirely clear, but most likely the single, giant sperm cell fills the female spermatheca (a sperm storage space that allows the female to inseminate eggs long after the copulation) and precludes her from mating with other males.

I wish I could have spent more time in Georgia – it would have been nice to see armadillos in a form other than flattened pancakes on the highway. On my drive from Savannah to Atlanta I counted 27 carcasses of these animals killed by cars.

I wish I could have spent more time in Georgia – it would have been nice to see armadillos in a form other than flattened pancakes on the highway. On my drive from Savannah to Atlanta I counted 27 carcasses of these animals killed by cars.

As I drove back from Savannah to Atlanta, counting armadillo roadkill (27), I couldn’t help but wonder what the bar scene of our species would look like if men produced only one, 6 feet long reproductive cell during each mating. In the end, I am happy for the zorapteran males, but will keep my millions, thank you very much.

Zorapteran (Zorotypus hubbardi), the only species of the order Zoraptera found in the United States.

Zorapteran (Zorotypus hubbardi), the only species of the order Zoraptera found in the United States.

BugShot 2014: Sapelo Island, GA

Polyrhachis

Intimate portraits: A queen ant (Polyrhachis armata)

My arrival in Johannesburg has brought a welcome respite from the unbearable winter of New England, and tomorrow I fly to Gorongosa National Park to begin preparations for the official opening of the E.O. Wilson Biodiversity Laboratory on March 27th. Stay tuned for updates and photos!

But there is something else that I am very excited about. Last year I was invited by Alex Wild to teach an insect photography workshop in Belize, the famous BugShot, and this year we are doing it again. This time the workshop will take place on Sapelo Island in Georgia, a place I have never been to but always wanted to visit. Insect life is bound to be spectacular – among other things I expect to find there Brunneria borealis, North America’s largest praying mantis and the world’s only fully parthenogenetic species of these insects. There are webspinners (Embioptera) there, two species of sylvan katydids (Pseudophyllinae), and over 100 species of other orthopterans. This is going to be good.

High-speed macrophotography: Periodical cicada (Magicicada septendecim)

High-speed macrophotography: Periodical cicada (Magicicada septendecim)

The workshop will take place on May 22-25 and there are still a few empty slots left. If you want to learn macrophotography, perfect your technique or learn a new one, or simply find out amazing facts about invertebrates, then you should join entomologists and photography experts Alex Wild, John Abbott, and myself on this fun adventure. Visit the BugShot website to find more details.

Wide-angle macro: Sylvan katydid (Celidophylla albiomacula)

Wide-angle macro: Sylvan katydid (Celidophylla albiomacula)

Time lapse macrophotography: A molting katydid (Enyaliopsis petersi)

Time lapse macrophotography: A molting katydid (Enyaliopsis petersi)

Ambient light macrophotography: Atlantic shield-back (Atlanticus testaceus)

Ambient light macrophotography: Atlantic shield-back (Atlanticus testaceus)