Midges refer to a group which includes many kinds of small flies. Some species of midges, such as the Phlebotominae (sand fly) and Simuliidae (black fly), are vectors of various diseases. Many others play useful roles as the prey items for insectivores, such as various frogs and swallows. Others are important as detritivores, participating in various nutrient cycles. The habits of midges vary greatly from species to species; though within any particular family midges commonly have similar ecological roles.

Examples of families that include species of midges include:

1. Blephariceridae, net-winged midges
2. Cecidomyiidae, gall midges
3. Ceratopogonidae, biting midges (also known as no-see-ums)
4. Chaoboridae, phantom midges
5. Chironomidae, non-biting midges
6. Deuterophlebiidae, mountain midges
7. Dixidae, meniscus midges
8. Scatopsidae, dung midges
9. Thaumaleidae, solitary midges

Midges are any of a group of tiny two-winged flies (order Diptera) that superficially resemble mosquitoes. Although they resemble mosquitoes, midges are harmless, with small mouthparts that are not elongated into a piercing structure for blood feeding. They do not have scales on wings or body, and the pattern of wing veins differs from that of mosquitoes. The male antennae are feathery, which gives them a distinct look. Midges are usually found around ponds or streams in late afternoon and evening in swarms that produce a humming sound. Midges may breed in water or manure or under tree bark.