Author Archives: Brian Brown

Gardening for flies 4. Use Baccharis.

I recently witnessed and photographed an incredible assemblage of insects. They were on flowering female plants of Baccharis ‘Centennial’, a widely available hybrid of a plant commonly known around here as “coyote bush”. It was used extensively in what we call the 1913 Garden at the Natural History Museum of Los Angeles County, where I work.

For the last couple of weeks, the plants have been swarming with insects, including many Diptera. In fact, I was first alerted to the situation by Richard Hayden, our Head Gardener, who described a swarm of flies in the area. We went to check it out, and I had my first view of the seething mass of insects on and around the plants, apparently feeding on nectar.

The following photos are only a few of the flies on this swath of Baccharis in downtown L.A. I suggest using this plant in any insect-friendly landscape.

a female bibionid

little blood-red flower fly

thick-headed fly

Best book ever on flies

Steve Marshall’s new book “Flies: the natural history and diversity of Diptera” is the best book ever on flies. It is so stuffed with amazing photographs and interesting information that I literally cannot tear my eyes away from it.

fly-book

I showed it with my hand for scale because it is HUGE. Steve could have written a book half this size and it still would have been the best book ever on flies, but he really overshot the mark here. The number of photos of flies in this book is absolutely insane. I mean, there five pages of photos of sphaerocerids (lesser dung flies), never mind the page after page of more photogenic groups!

Steve was my MSc advisor and has remained a good friend through the years since. We’ve even traveled together and I’ve seen him clicking away with his camera while collecting at the same time, but I had no idea that he had THIS in him. Simply a remarkable book from a remarkable guy. If you are even slightly interested in Diptera, don’t stop to think, just buy this book as reflexively as you take your next breath. Its that good and I can’t imagine anyone writing one that is better.

A new fly to study

Some European colleagues were kind enough to send me specimens of a fly that I have never seen before: Opetia nigra. It is classified in its own family, Opetiidae, a group not known from the New World, but in the past has been most frequently placed in the family Platypezidae, the flat-footed flies (I kid you not; don’t blame me for these common names!).

Opetia nigra male; photo by Inna Strazhnik

I wanted to see specimens because they are a family that are probably related to my Phoridae, although the precise relationship remains elusive. Hopefully, my studying the structure of these flies will tell us something new, although they were treated in great detail by Peter Chandler in his recent book on the flat-footed flies of Europe.

Phorid flies and frogs

Phorid flies are characterized by my colleague, Henry Disney, as the most biologically diverse family of insects. With each passing year, we find more and more unusual lifestyles and larval food preferences that support this statement.

Female Agalychnis spurrelli. Photo by R. Horan III


In the New World tropics, there are a huge variety of frogs found in rain forests. Many of them live in the canopy and come down to the ground level only for mating. Often they lay their eggs on leaves over water bodies, apparently to try and limit depredation by aquatic predators. This creates an opportunity for phorid flies.

My co-author, Robert Horan III, found that eggs of the gliding leaf frog, Agalychnis spurrelli, were turning a strange white color in his study on Barro Colorado Island in Panama. Further investigation showed that maggots of a small fly were eating the eggs. He reared some adults, sent them to me, and they turned out to be a new species that we named Megaselia randi. The name was a tribute to an influential herpetologist, Stan Rand, who helped Robert in his early career.

Healthy frog eggs. Photo by R. Horan III.

Infected frog eggs. Photo by R. Horan III.

This is not the first instance of phorid flies feeding on frog eggs in Latin America. Frogs in two other genera, Phyllomedusa and Leptodactylus, are also attacked. A colleague of mine recently contacted me about a frog egg feeding species in Ecuador.

Phorid larvae in eggs. Photo by R. Horan III.

There are probably thousands of species of Megaselia in the Neotropical Region, most of which are unknown, and the lifestyles of the 350 or so known species are also relatively unstudied. It is possible that among them there are a whole range of flies attacking frog eggs. Herpetologists, keep the possibility of phorid flies in your mind!

Reference: Brown, B.V. & R.V. Horan, III. 2011. A key to Neotropical Region frog-egg-feeding species of Megaselia (Diptera: Phoridae), with a new species from Panama. Contributions in Science. 520: 1-4

Phorid parasitoids of endangered ants also endangered

When ant-decapitating flies have endangered hosts, they become endangered, too. Today in the journal Zootaxa, I describe three new species of phorids found by my co-authors Marcos A. L. Braganca, Diego S. Gomes, Jarbas M. Queiros, & Marcos C. Teixeiras. The three flies attack Atta robusta, a species of ant found only in restinga (sandbank) vegetation in a small area in Brazil. Two of the flies are Eibesfeldtphora species, while the other is a Myrmosicarius; all are parasitoids developing in the ant’s head. We don’t have photos, but I am taking the opportunity to show a couple of fabulous photos of another Eibesfeldtphora attacking leaf cutter ants in Costa Rica by Wendy Porras.

Eibesfeldtphora curvinervis about to attack a leaf cutter ant. Photo by Wendy Porras.

The fly laying an egg into the ant’s head through the occipital foramen (neck). Fabulous photo by Wendy Porras.

Terrifying photos. If these flies were the size of crows we’d never leave our houses!

Home of the world’s smallest fly

The world’s smallest fly (0.40 mm long) was collected at Kaeng Krachan National Park in Thailand, the country’s largest.

It is a beautiful place with hot lowlands and misty highlands where the forests are crawling with land leeches.

There are many large mammals in this park, including leopards.

We conducted a training course for the Thai parks staff who would be helping us; here is Mike Sharkey leading the group on how to properly use a Malaise trap. The fly, Euryplatea nanaknihali, was collected by one of the many traps placed in this field.

Worlds smallest fly discovered

In a paper appearing today, Monday, July 2, 2012, I describe the world’s smallest known fly. It was collected during the TIGER (Thailand Inventory Group for Entomological Resources) project, funded by the National Science Foundation with the grant to Dr. Michael Sharkey of the University of Kentucky and me (as co-PI).

Many stories about small things, especially parasites, quote Jonathan Swift:

“So, naturalists observe, a flea
Hath smaller fleas that on him prey;
And these have smaller still to bite ’em;
And so proceed ad infinitum.”

In this case, the quote is especially apt, because the newly discovered worlds smallest flies are parasites!

The smallest fly in the world is a member of the family Phoridae, and is one of the “ant decapitating flies”. Adult females lay an egg in the body of an ant, and the resulting larva feeds in the ants head, eventually causing the decapitation of its host. Some of these flies are being used to attempt biological control on imported fire ants, and were even featured on an episode of the popular television show “King of the Hill”.

Because these flies usually develop in the head of their host ant, they are smaller than their hosts. One would think that the smallest ants would be therefore immune to these nasty parasites, as their heads are vanishingly small. But the world’s smallest fly is one of these ant killers, and at the astoundingly small body length of 0.4 mm, these flies can probably decapitate ants with heads as small as 0.5 mm. That is pretty close to the smallest size that ants can get!

When we think of animals that are small, usually a fly or a flea come to mind. Let’s forget about fleas; they are comparative monsters at around 1-2 mm in length. But what about flies?

The common house fly is something that we think of as being small. In the world of tiny insects, however, they are virtual Godzillas at a whopping 6 mm.

Many flies are much smaller than this. Fruit flies that you see hovering over overripe bananas, for instance, are about 2 mm long, one third of the size of the “giant” house fly.

Some of the biting flies are much smaller than this. One aptly named family of flies has the common name “no see ‘um”, because of their almost invisibility when they are biting you. These flies are getting really small, usually around 1 mm in length.

The world’s smallest fly is 0.4 mm in length. Here is a microscope slide, 1″ x 3″ size, with the holotype specimen of the fly mounted on it. It’s unimaginably small, smaller than a flake of pepper you shake out of the pepper shaker.

holotype specimen of Euryplatea nanaknihali Brown

Do you see it, within the small circle, to the right and slightly above center?

The world smallest fly doesn’t really look like a fly. It’s one of those weird phorids whose body form we call “limuloid”, after Limulus, the horseshoe crab. It is a defensive body form that allows the flies to live in the ant nest which, based on this body structure, is probably part of the fly’s life. It has short wings, but they are functional sized, so this fly could easily fly from ant nest to ant nest. It also has a sharply pointed tip of the abdomen, indicating that it is a parasitic species.

My research is funded by the National Science Foundation, currently grant No. DEB-1025922.

Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author and do not necessarily reflect the views of the National Science Foundation.

Massive tropical fly inventory funded by the United States National Science Foundation

A tachinid fly photographed by Wendy Porras at Zurqui

I am excited to announce that NSF has funded Dr. Art Borkent and I to conduct an ambitious project to discover and enumerate all of the flies at a tropical site in Costa Rica. The site, called Zurqui de Moravia, or Zurqui for short, is about one half hour north of San Jose in the cloud forest just outside Braulio Carrillo National Park. We have been collecting there for the past 15 years, and have found one of the most diverse and interesting faunas in Costa Rica. Now we are extending our studies to ALL of the Diptera found there!

This project is a collaboration of more than 40 experts worldwide, as well as Costa Rica’s Instituto Nacional de Biodiversidad (INBio). Together, we will collect extensively and identify all groups, even the “impossible” ones like ceratopogonids, cecidomyiids, and phorids. We expect to find a number of species that will surprise even us!

This will be the first time that such an intense effort will be made for any mega-diverse group of insects in the tropics. We were inspired by Terry Erwin’s fogging samples in Peru (and elsewhere), but wanted to go a different route in understanding tropical biodiversity. The “All Taxon Biodiversity Inventory” (ATBI) model appealed to us, but we knew we had to restrict our collecting to prevent the project from getting out of hand. We therefore decided to collect in just two small ravines in an area 100 m x 200 m in size.

We are calling the project the “Zurqui All Diptera Biodiversity Inventory”, or ZADBI. Collecting will start in September; meanwhile we are getting organized for the massive job of collecting, preparing, and identifying the tens (or hundreds) of thousands of specimens we will collect. Of course, we will be broadcasting our discoveries and experiences both here on flyobsession and on the project’s website (TBD). Get ready for some more cool flies!