Monthly Archives: December 2011

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 3..

Actually we are farther in than 3 days. We are staying in a town called Monte Negro, and have 2 collecting sites: one about 10 km from here, and one about 50 km from here.

On day 3, we went to the 50 km site for the first time. It was seething with insects, from butterflies and uraniid moths to stingless bees and higher flies. We put up 3 of our Townes style Malaise traps, while my colleague, Dalton, and his 2 students put up a huge Gressitt-style, double headed trap. Instantly, this giant black trap became a drawing card for the local insect population. The trap was literally heaving with all the insects inside it and coating the outer surface. Rather than wait for the insects to possibly fly into the collecting bottles, Dalton swept them with an insect net. He made impossibly huge collections of tachinids, syrphids, strats, and myriads of smaller flies.

Dalton sweeping out his trap

I sat down beside the trap, and took a few photos without moving; you can see the diversity of fabulous larger flies here in the following photos.

syrphid fly

for Chris Raper - how is this for tachinid density?

tachinid fly

another tachinid fly

yet another tachinid fly

a final tachinid fly

It is unusual to see such overwhelming diversity, but sometimes it happens. We went back to the same site yesterday and all of our traps were stuffed full to the top, mostly with unwanted Lepidoptera. These we had to laboriously remove from the samples to find the more interesting (to us) material, a process that takes hours upon hours.

As for phorids, we found lots associated with ants, but the best phorid so far was in a Malaise trap sample. The attached photo isn’t the greatest, but it is the best I could do in the field with the fly less than 1 mm long. It is a male Brachycosta, the first I have seen.

tiny male of Brachycosta

Next post: a new discovery in ant decapitating fly behavior.

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?

Brazil expedition: day 1

forest across the Rio Madeira

Actually, this is day 2, but it is day 1 of collecting. Yesterday, we (Giar-Ann Kung, and I) arrived at the same time as our Brazilian colleagues: Dalton Amorim, Danilo Ament, and Paula Riccardi. We did our shopping in Porto Velho, got a hotel, went out for dinner, and got ready for the next day.

Our main base for collecting in Rondonia is at Monte Negro, about 50 km from Ariquemes, but this wouldn’t be open to us until later in the day (it’s a Sunday). Dalton’s idea was to drive across the Rio Madeira and collect on the other side. This is particularly interesting to do because the Rio Madeira is a conspicuous breaking point for the distributions of many Amazonian creatures. Thus, on one side of the river you should get one species, and on the other side another.

unfinished bridge over the Rio Madeira


We were game, but there was no bridge. Seems the bridge is under construction, so we took a barge driven by a tugboat across the river as a ferry. On the way across we saw one river dolphin.

ferry

We also saw lots of forest destruction. Rondonia is still one of the frontiers of Amazonia, but it’s going fast. We were a skeptical that we would find decent forest close to Porto Velho. When we got across the river, however, we saw on our right quite a bit of good-looking forest. We pulled over to the side of the road to a small building in order to ask permission for access to this forest. While Dalton was in the building, another car pulled up beside us, and it turned out to belong to the owner of the site. Dalton talked for a few minutes to this very friendly fellow, who was more than happy to allow us to have access for our collecting.

We drove on a dirt road for just a couple of kilometers before stopping in some pretty decent forest. According to the owner, there were monkeys, tamarins, and other mammals still in the forest; sadly, however, the site was slated for urban development.

most of our field team


We put up two Malaise traps, and then collected there for a couple of hours. Danilo found an ant nest in a rotting stump, and collected some phorids there. The ants turned out to be a Pheidole colony, from which we got 2 to 3 species of Apocephalus ant decapitating flies. Danilo also found a colony of Dolichoderus ants, from which we collected two Microselia females, a relatively rarely collected parasitoid genus.

All too soon, it was time to leave. We packed up everything except the Malaise traps, which we left to collect, went back to the hotel to clean up, and then did the 3.5 hour drive to Monte Negro. We’re going back to the other side of the river for a couple of days on our way back, though. It’s a great spot, full of diversity, and we might as well salvage some of what’s there before it’s all destroyed.

Tomorrow: our 1st field day at Monte Negro.

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