midge, name for any of numerous minute, fragile flies in several families. The family Chironomidae consists of about 2,000 species, most of which are widely distributed. The herbivorous larvae are found in all freshwaters; the larvae of some species live in saltwater. Midge larvae are an important source of food for larger aquatic insects and fish. The larvae of some species of the genus Chironomus, which are called freshwater bloodworms, are unusual in that they contain the protein hemoglobin. The pupae are active and aquatic. The adults, which look like slender mosquitoes, are often seen swarming over or near water, and large courting and mating swarms may contain millions of insects. The larvae and pupae of the net-wing midges, family Blepharoceridae, live in fast-flowing freshwater; they attach to rocks by suction disks and feed mainly on algae. The biting midges belong to the genus Culicoides of the family Ceratopogonidae; they are the smallest of the bloodsucking insects and are common pests in the NE United States, where they are called punkies, sand flies, and no-see-ums. The adults have mouthparts that pierce and suck and inflict irritating bites on humans; some species ride the wings of dragonflies and lacewings, sucking the blood of their hosts. Gall midges, family Cecidomyiidae, damage many plants by causing formation of plant galls in which the larvae live (see gnat). Midges are classified in the phylum Arthropoda, class Insecta, order Diptera.

Any of a group of tiny dipterans, sometimes called gnats and classified as nonbiting (family Chironomidae), biting (family Ceratopogonidae), or gall (family Cecidomyiidae) midges. Nonbiting midges resemble mosquitoes but are harmless. Humming swarms can be found around water in late afternoon. The often blood-red, aquatic larvae (bloodworms) are important food for aquatic animals. Biting midges (no-see-ums) are the smallest bloodsucking insect (about 0.04 in., or 1 mm, long). Punkies or sand flies (genera Culicoides and Leptoconops) attack humans but do not transmit disease; many species attack other insects. Gall-midge larvae cause tissue swellings (galls) in plants.

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