Any member of the more than 85,000 species in the insect order Diptera (the two-winged, or "true," flies), characterized by the use of only one pair of wings for flight and the reduction of the second pair of wings to knobs used for balance.
Dipterans live in all habitats worldwide, including the subarctic and high mountains. They range in size from about 0.05 in. (1 mm) long ( robber flies ). Dipteran larvae break down and redistribute organic materials, and both adults and larvae are a significant link in numerous food chains. Many species are annoying bloodsuckers, and several (e.g., {{link=housefly">housefly , mosquito , sand fly , tsetse fly ) are vectors of disease. Other species cause great damage to agricultural crops. See also blowfly , crane fly , fruit fly , gnat , horsefly , leaf miner .