Tour de Fly

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Published on: May. 2, 2003

Last revision: Nov. 15, 2010

stable fly, Stomoxys calcitrans. It is related to the house fly and closely resembles one, except for the needle-like beak. Both sexes take blood from a variety of hosts. Harassment of cattle by stable flies, as well as horse flies, can cause a decrease in milk production and disrupt grazing patterns. Stable flies rarely breed in manure, preferring decaying grass clippings, wet hay and compost.

Among our largest flies are the mydas flies (Mydidae), which frequent forest margins. Mydas clavatus is a mimic of a large spider wasp, with a red band on its black abdomen, and shimmering violet wings. The larvae may be predatory on scarab beetle grubs.

A wealth of flies are parasites of other insects. Chief among these are the Tachinidae. Tachinids usually have very bristly or spiny bodies. Females can use devious tactics to access their hosts. Some species lay hundreds of minute eggs on foliage near their caterpillar targets. The caterpillars consume a few eggs in the course of feeding, and the maggots that hatch slowly consume their host internally.

Adult Trichopoda have feather-like scales on their hind legs that resemble the "pollen baskets" of bees. Trichopoda glues an egg atop a squash bug or stink bug, where the victim cannot reach to wipe it off.

Bot flies of the family Oestridae are parasites of mammals, living as larvae in such unthinkable places as the stomach lining of horses (Gasterophilus), sinus cavities of deer (Cephenemya), or under the skin of rodents (Cuterebra). The adult flies approach the size of bumblebees, but are rarely seen. Most species have no mouths, living off stored fat accumulated in the larval stage. Once thought to fly faster than the speed of sound, it is now known they seldom exceed 25 miles per hour. Still, livestock are known to panic at the approach of these insects.

Most blow flies in the family Calliphoridae dine on deceased bodies, and are indispensable agents of decomposition. The familiar "bluebottles" like Cynomyopsis cadaverina and Calliphora vicina, are named for their iridescent blue abdomens. Phaenicia sericata and Lucilia illustris are common, bright metallic "greenbottles."

Although they grow up in rotting flesh, they are competent pollinators of wildflowers. The black blow fly, Phormia regina, can be found as an adult every month of the year.

These species, and the secondary screwworm, Cochliomyia macellaria, are important to forensic scientists in Missouri. Some blow flies appear on the

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