Tag Archives: tropical

New frontiers in Costa Rica

Tapanti NP

My late colleague, the hymenopterist Roy Snelling, used to ask me disdainfully, “why go to Costa Rica; everything is already known from there.” Even Roy knew, however, that this wasn’t true. His mistaken assertion was that so many people had collected in CR that, given the large number of other places that had not received any attention, it would be a waste of time to go back to a small Central American country.

I disagreed with his statement for many reasons. First of all, there aren’t enough dipterists on the planet to make even a tiny part of CR “overcollected.” There are so many habitats and microenvironments in a country with a mountain range down its center in the tropical zone, that doing an inventory of all of Costa Rica is probably impossible. From dry tropical forest in the northwest to the near treeline heights of the Cerro de la Muerte, and all the rain forest inbetween, CR is a biodiversity paradise.

But more interestingly, it is possible to find new frontiers in the same sites by using different collecting techniques. Last year, for some reason, we decided to try blacklight collecting in Costa Rica for the first time since my trips in the 1980s. We used a trap of my design that was so successful, I decided to write it up for publication (watch for it in Entomological News).

Using this “old” technique again, we managed to wring out some incredible specimens of Phoridae and one special sphaerocerid from a mid-elevation site from which we otherwise had no special expectations.

For phorids, our technique yielded new specimens and a new species of a genus previously known from only a couple of females from elsewhere in Costa Rica. This genus is marked by incredible huge palps with outrageously long apical setae. Additionally, we got some parasitic phorids I had never seen before, as if we had gone to an entirely new continent. Believe me, I have gone through hundreds of samples Costa Rica, and have looked at least 50,000 specimens from this country, so when I see a congregation of new things, I take notice.

the phorid with huge palps - a fuzzy photo

The sphaerocerid was the second known specimen and species of the genus Podiomitra of the incredibly rare subfamily Homalomitrinae. Although I’m not an expert on these flies, I knew as soon as I saw it that it was something special.

Podiomitra sp.

Bottom line: we have to keep trying new collecting methods, even if they are old collecting methods. I’m going back to Costa Rica at the end of February, and I’ll be bringing my lights again!

How we started working on “rare” bee-killing flies

The most beautiful phorid flies are in the genus Melaloncha, also known as bee killing flies. I have no small bias in this statement, however, since I worked on them for several years and grew to be very fond of them.

Melaloncha punctifrons, female

One of the allures of these flies was their rarity when I first started. In all of the collections I surveyed, I could find only a few specimens, about 100 in total. There were many new species among these specimens, however, so I knew that the 32 described species was only the tip of the iceberg. But how was I to uncover the rest of that iceberg?

Many parasitic phorid flies seem to be attracted to masses of their hosts. Logically, aggregations of hosts should create aggregations of parasitoids, so Giar-Ann Kung and I decided to try to make aggregations of stingless bees, the known hosts of these flies. Monty Wood, a fellow dipterist who works on tachinid flies, told me that when he sprayed a mixture of honey, Coca-Cola, and water onto undergrowth vegetation in an attempt to attract his flies often attracted huge aggregations of stingless bees instead. Therefore we tried spraying honey and water, and were almost immediately successful in attracting bees, and eventually flies. There was one other required condition, however: it had to be in the sunlight, or the flies would not be attracted. This is contrary to most phorids, which tend to be more active in shade.

Melaloncha acoma attacking stingless bee

Once we adopted the honey spray and sunlight combination, we started collecting large numbers of these flies, eventually collecting thousands of them. Sometimes, we were almost too successful in attracting the bees, producing gigantic aggregations that made it impossible to breathe or see anything, necessitating the use of jury rigged bee veils. These consisted of an insect net placed over the head and sealed around the neck with rubber bands. Eventually, though, the tiny stingless bees would get in, and we’d have to beat a retreat to get the annoying things out of our eyes, ears, and noses.

Me wearing a jury-rigged "bee veil" in Argentina, 2003

It was all worth it though, as we ended up catching 50-100 Melalonchaper day at good sites, and found almost 150 new species. I think there are still many more out there to find, so we keep spraying honey wherever we go in the tropics, and keep finding the beautiful, but deadly (to bees) bee-killing flies.

Melaloncha xanthocauda, femal

Melaloncha berezovskiyi, female

Melaloncha acoma, female

Brazil expedition 6 – Smoke

One of the weirdest happenings on our trip occurred on the way back to Porto Velho. As we were driving along, I saw a smoldering pile of wood and trash along the road. “Let’s stop and try for Microsania” I suggested. Everyone was hot and tired, the site was far from any good habitat, and it was about to pour rain, but Dalton good-naturedly indulged my request. I jumped out of the car, ran over to the smoking pile with a borrowed net, took a few sweeps, and beat a hasty retreat to the car (it was terribly hot from the fire), where everyone else looked at me skeptically.

Me collecting Microsania in smoke

“I got some,” I said. “Those were already in the net,” someone suggested. But no, they were “smoke flies,” species of the platypezid genus Microsania. Most were males, as they assemble mating swarms in smoke- nobody really knows why. Smoke flies are known from around the world, but remain rare in collections, only because we rarely bother to sweep in smoke! At any rate, we caught a lot of them that day.

male Microsania

This concludes my reports from Brazil. It was a productive trip, but the heat, mosquitoes, and travel made things fairly tough. Also, one member of our group got stung in the stomach by a big wasp and had to be rushed to the hospital due to a bad allergic reaction. The forest is going fast, but there are still large areas to explore and discover. I can’t wait to go back there.

Note: all specimens we collected in Brazil are deposited in the Zoology Museum of the University of Sao Paulo.

forest destruction

Brazil expedition 5

One of the great things about traveling with other people is that you get to see new ways of doing things. This includes new ways (for me) of collecting flies.

Dalton brought along a Shannon trap, named after the dipterist R.C. Shannon. Dalton’s version is a big, 8′ x 8′, fine mesh box that is open underneath. It is suspended in the air by stakes and string, with just a couple of inches clearance above the ground. Under the trap goes the bait, and this is the mind boggling thing.

Shannon trap


For bait, Dalton used: a whole fish, chicken parts, raw beef, flour, vegetables, fruit, and onions, all heaped together in a one meter square under the center of the trap. The idea is that insects are attracted, and then when they try to escape, they fly upwards and are caught in the trap. The collector could visit the trap, get inside it, and collect what they want.

Well, this trap, after a few days of bait ripening, was a seething mass of flies, moths, and butterflies. It may seem strange, but butterflies and moths are strongly attracted to decaying organic material, just like the flies. One of the most common moths here right now is a beautiful day flying uraniid moth, and we had to fling handfuls of them out of the trap in order to see anything else. Dalton got in and swept around with his net to clean out the flies, but after he was done I was able to photograph some of the leftovers on the reeking pile of decay. Here are a couple of the insects that were attracted.

uraniid moth

happy blow flies on chicken

Mesembrinella

Cyphomyia sp,

Also present, as you might imagine, were fly larvae, or maggots. Some of the attracted beetles were busily gobbling them up, but see what happens to the predatory staphylinid beetle in the video below.

Brazil expedition: day 4

As many of you know, I work on phorid flies, including those known as “ant decapitating flies”, genus Apocephalus. These flies dart down at their hosts, laying an egg in the host body (usually the head). The egg hatches, and the resulting larva feeds inside the ant’s head capsule, consuming about all of the contents of the head. Now, the inside of ants head is not like yours or mine, full of brains; instead, they have huge muscles inside their head capsules to move their massive mandibles (mouthparts). The insect brain is an insignificant little shred of material compared to ours. Anyway, the larva feeds, and eventually the ants head falls off, sometimes before the rest of the body finishes walking around – hence the name “ant decapitating fly.”

There are almost 300 described species of these flies, but we think there are perhaps 200 or 300 more. Therefore, we’re down here collecting, and trying to understand some life history information. We were able to solve one little mystery on this trip.

A couple of years ago, we saw workers of a species of the ant genus Pheidole being attacked by an Apocephalus species, in which the flies seemed to be darting at ant larvae, rather than the adults. We saw the same thing here, and studied it in a little more detail. We even got some video of the flies 

We cut open an old dead log and found a nest of Pheidole. In short order, we had dozens of flies attracted to this exposed colony. We saw the flies darting at the ants when they were carrying larvae, as in our previous observation. We saw, however, that the flies were actually attacking the ants, and not the larvae.

The ants seem to be quite aware of the presence of the flies, and keep their mandibles in the air apparently trying to snap and grab the flies. The ants are highly agile and fast, so this seems to be a formidable defense. Apparently, the flies wait until the ants pick up a larva or pupa before attacking them, as their defense is neutralized when carrying a burden. This seems to me an amazing behavioral adaptation, but it might be commonplace, given our poor understanding of ant/parasitoid interactions.

Brazil expedition: day 2

It is hard to do fieldwork and maintain a blog, especially after a busy day like today. We got up early, went to a café and had horrendous coffee, did some shopping for a few supplies, and then went to the field. A local ambulance driver showed us to a site about 10 km from town. There, we found pretty good 2nd growth forest, and had some good collecting as well. We put up four Malaise traps, crushed various ants to attract parasitoid phorids, chopped open rotten logs to find ant nests, and even saw a fantastic raiding party of Pachycondyla commutata, a ponerine ant that raids in groups and comes back with a huge termite in each worker’s mouth.

These things are what people expect of fieldwork, I imagine. Let’s add a few more details of reality. This is hard work. You are on your feet all day, walking back and forth, carrying water, alcohol, traps, collecting gear, and various other baits and gear. It is extremely hot and humid here, and sweat drips off my face constantly, all day. It takes a couple of days for your body to adapt to such a different temperature and humidity regime, after which you don’t need to regularly drink liters of water, or sweat so prodigiously.

There are mosquitoes and other biting flies here, but they aren’t such an annoyance during the daytime. That role is played by the tiny stingless bees that constantly swarmed around your head, in your ears, in your eyes, and even crawling into your mouth trying to find moisture. It takes a couple of days to learn to ignore them, too.

A day of this type of work lasts until about 3 PM, after which you are usually exhausted, but happy after finding so many cool, new things. But there is work to do: sorting the day’s catch, labeling, and cleaning the samples. This goes on until dinner time (fortunately, we hired a cook, so we don’t have to do our own food preparation), about 6:30 PM, and continues into the night until either the work is done, or you are too burned out to do anymore. Of course, this is the time when you often find something rare or exciting, like we did tonight (but I’ll talk about that tomorrow). Tonight, on our second field day, we stopped working at about 9:30 PM. Cleaning up takes about another half hour.

Neriid fly

Therefore, at 10 o’clock, I finally have time to think about writing the blog. Since we are getting up 6 AM tomorrow to see a new, more distant site from our base, blogging takes the place of sleep. I think I need to bring someone along to do the blogging for me. Any takers?

Weird female Phoridae – Part 3: World’s weirdest fly?

Females of the genus might be the weirdest flies on earth. I don’t say this lightly. Like everyone else, I gazed in open mouth shock at the pictures in Naturewhen it was first described. The fly looks exactly like an ant larva with the head and thorax of a phorid fly glued onto it. And, oh yes, the wings and legs are absent!

female Vestigipoda

Later, researchers published photos of these adult female flies being carried about by their host ants, apparently treated just like the ant larvae. And how did they know they were adult females, you might ask? Well, they published a photo of a slide mount of one of the flies with an egg coming out the end of the reproductive tract.

This is one of the wonders of the natural world, as far as I’m concerned. I have never seen one alive, but my colleagues Henry Disney and Munetoshi Maryama were kind enough to send me some specimens.

The flies are found in nests of the southeast Asian ant genus Aenictus, with specimens from Malaysia and Thailand having been recorded.

Field work

For many of us, going to the field is what we like most about Dipterology (the study of flies). The chance to find new species, experience different environments and cultures, and more than anything, the opportunity to slow down; these are the rewards of the field.

I am on an airplane to Brazil to work with my colleagues Dalton Amorim and his PHD student, Danilo Ament. We have a long-term collaboration based on shared work on phorid phylogeny, thoracic morphology, and tropical inventory. Camaraderie is another pleasant aspect of field work.

This time, we are going to Rondonia, in the southern Amazon. It promises to be a trip of amazing discoveries, as very little collecting has taken place there, other than at Rancho Grande, a formerly popular collecting site that apparently doesn’t have any forest any more. We are going to stay at another area, called Monte Negro, and make excursions from there. Every day (I hope), I will post about our finds, to give the flavor of a tropical Diptera expedition.

For now, I’m just trying to endure the long flights…

A wasp-mimicing flower fly from my last field trip in Costa Rica