Our insect collection has its roots in an amateur collection. Predictably, that means our holdings are very strong in two orders popular with collectors – butterflies and moths (Lepidoptera) and beetles (Coleoptera). We had, at last count, about 130,000 pinned Lepidoptera and 240,000 pinned Coleoptera in the museum. In recent years, however, our primary research focus has been on the flies (Diptera) and our fly collection is growing by leaps and bounds. We have more than 350,000 pinned specimens and are growing by tens of thousands each year. Yet, despite the size of the Diptera collection, and despite the fact that Diptera have arguably a greater impact on human life than any other order of insects, many of our visitors wander quickly past the Diptera cabinets to go and see the butterflies and beetles. We see the same trend on the web, with lots of sites and blogs extolling the virtues of the (admittedly fascinating) leps and beetles; there are far fewer devoted to the glory of flies.
Our colleague Brian Brown at the Natural History Museum of Los Angeles County has made an excellent start on addressing this lack of attention with his new blog flyobsession. Another Canadian colleague, Morgan Jackson at the University of Guelph, has great fly content in his Biodiversity in Focus blog. For a more museum-centric perspective, check out Erica McAlister’s Curator of Diptera’s blog from the Natural History Museum in London (one of the world’s great fly collections). Another UK blog is Chris Raper’s, which has a big focus on the Tachinidae, one of the families that I love to look at, but that gives me nightmares when I sit down to identify specimens (I’ll need to spend more time with tachinids). I’m sure there are more great fly blogs than those I’ve listed here. It’s a big internet.
Given our fly focus here at the museum, we feel compelled to contribute to the global marketing effort for Diptera. It’s human nature to love lists, especially, apparently, Top Ten lists. In that spirit, we present the first in a series of posts on More Than Ten Reasons Flies are Great. To ensure that not everybody abandons all those other orders all at once to become Dipterists, we’ll start with five:
1. Chocolate. Chocolate comes from cocoa pods. Cocoa pods are produced when cocoa flowers are pollinated. The main pollinators of cocoa flowers are ceratopogonid midges in the genus Forcipomyia. Forcipomyia says “You’re welcome”
2. Cleaning the beach. Dead and dying algae washes up on beaches, often in huge amounts, to form accumulations of wrack. The main decomposers of this wrack on ocean beaches are the larvae of Diptera in several families including Sphaeroceridae, Coelopidae, Helcomyzidae, Canacidae and Anthomyiidae. Kick into a big wet pile of wrack when you walk along the beach and hundreds of flies will take to the wing and even greater numbers of larvae will be seen crawling through the mass. Without this enormous assemblage of fly larvae breaking down the wrack and making it available to other decomposers such as bacteria and fungi, many ocean beaches would be completely covered with rotting seaweed.
3. Drosophila melanogaster. Most of what we know about genetics, we know because of this little yellow fly. Why this species? Because a hundred years ago, in the infancy of this field of biology, they were easy to obtain, easy to rear, easy to breed, and didn’t take up much space in a lab, so Thomas Hunt Morgan, one of the pioneers of modern genetics, chose them as his study organisms. Advances in science are often driven, in part, by convenience. Flies, in this case, were very convenient.
4. Ant-decapitating phorids. There are many ways to be parasitic, but only a few are this spectacular. Some phorid flies in the genera Apocephalus and Pseudacteon lay eggs in ants. The larva finds its way into the ant’s head and feeds on the contents until the host ant is wandering around brainless, like a tiny, non-threatening zombie. A chemical secreted by the phorid weakens the membrane attaching the host’s head to its body and the ant’s head falls off. The phorid pupates in the now empty and antless head until the adult fly emerges. Delightful.
5. Survivors. Diptera survive and thrive in some of the harshest habitats on Earth. There are two species of multicellular animals in the main basin of Utah’s Great Salt Lake. One is a fly – the ephydrid brine fly Ephydra cinerea. Another species of ephydrid, Helaeomyia petrolei, lives in pools of crude petroleum. Myiasis-producing larvae in several families can go through their life cycle in the human gut, a nasty habitat for living animals. Some of the only terrestrial animals in Antarctica are chironomid midges. Some species of the phorid genus Megaselia are famous for the number of “habitats” from which they have been reared, including formalin-preserved museum specimens, paint and shoe polish, along with the slightly more normal bee hives, ant nests, stored food, rotten plants, dead bodies and dung.
Coming up in a future post: five more reasons, including bee riders, spider hunters, pollinators of strange flowers, and polar explorers.