Flies of the Family Micropezidae are commonly known as the stilt-legged flies because their middle and hind legs are unusually long. Not much is known about this curious family. Thirty-three species occur in North America, but many more are found in the tropics (1). Micropezidae larvae feed on dung, decaying vegetation and other organic matter. The adults are typically found in moist environments such as marshes; their feeding habits are largely unknown (2, 3). The specimen featured here is most probably Taeniaptera trivittata (another possibility is Rainieria antennaepes; both species look remarkably alike and occupy the same range). It was found next to a decaying tomato plant growing behind the greenhouses by the French Family Science Center. This particular species is an ant mimic. It waves its white-tipped forelegs like ant antennae and has a relatively narrow “wasp waist,” like an ant. The color pattern of the wings is such that when lying flat on their backs, they reinforce the image of the insect’s wasp waist.
(2) Borror, D.J. and R.E. White, A Field Guide to the Insects of America North of Mexico, (1987), Houghton-Mifflin.
(3) Arnett, R.H., Jr., American Insects: A Handbook of the Insects of America North of Mexico, (2000), CRC Press.