Flies belong to a group that also includes mosquitoes, gnats, and midges. There are about 100,000 species of fly. They live in almost every corner of the globe – in soils, plants, and around water bodies. Many flies are free-living, feeding off a wide range of plants, while others are parasites and scavengers. A number are of economic importance in controlling pest species, while others serve as vectors for a range of human, animal, and plant diseases.
Flies have a single pair of functional wings and a pair of knoblike vestigial wings known as halteres. Its head is free-moving and attached by a slender neck to the thorax. The fly has two large compound eyes. It has three pairs of legs, each ending in a pair of claws. Crane flies are exceptional in having extremely long legs.
Many species are a dull dung color. Hover flies are among the most colorful species, many of which are colored in similar patterns to bees and wasps.