gnat

gnat, common name for any one of a number of small, fragile-looking two-winged flies of the suborder Nematocera, order Diptera, which includes the families Tipulidae (crane flies), Bibionidae (hairflies), Ceratopogonidae (biting midges), Chironomidae (true midges), Cecidomyidae (gall midges), Simuliidae (black flies), Culicidae (mosquitoes), and others. They often assemble together in large mating swarms. In England mosquitoes are called gnats; in the United States it is chiefly the smaller forms of Diptera, especially irritating because of their great numbers and their vicious biting habits, that are referred to as gnats. All gnats have long, hairlike antennae, which are particularly well-developed in the males. Gnat larvae are free-living, most feeding on plants. Larval plant feeders, e.g., the Hessian fly larvae, cause root, stem, and leaf galls to be formed by the host plant. Some species of fungus gnats (families Mycetophilidae and Sciaridae) are very common pests of mushrooms and roots of potted plants in homes and greenhouses. One group of dipterans (family Chloropidae) of the suborder Cyclorrhapha are commonly called eye gnats, or eye flies. Gnats are classified in the phylum Arthropoda, class Insecta, order Diptera.

Any member of the insect family Simuliidae, comprising 300 species of small, humpbacked dipterans found worldwide. Usually black or dark gray, the blackfly has short mouthparts adapted for sucking blood. The females bite and are sometimes abundant enough to kill chickens and even cattle. Some species carry worms capable of causing human disease, including river blindness. In subarctic regions blackflies may be so numerous that human habitation is impossible.

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Any member of several species of small dipterans, most of which bite or annoy humans. Midges are also sometimes called gnats. In North America the name is also applied to the blackfly, fruit fly, and other small flies that hover about the eyes of humans and other animals.

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Gnat ("nat") is a colloquial name for many small insects in the order Diptera and specifically within the suborder Nematocera.

The males often assemble together in large mating swarms, particularly at dusk, called a "ghost".

Gnat larvae are mostly free-living and some are aquatic. Many feed on plants, though some are carnivorous. Larval plant feeders (e.g. the Hessian fly larva) cause root, stem, or leaf galls to be formed by the host plant. Some species of fungus gnats (families Mycetophilidae and Sciaridae) are very common pests of mushrooms and roots of potted plants in homes and greenhouses.

Some South American Pleurothallid orchids are pollinated by tiny gnats and have correspondingly small flowers.

Occasionally "gnat" is spelled "knat".

See also

• Black fly
• Eye gnat
• Gnat bug
• Gall gnats
• Sand gnat
• Dark-winged fungus gnat
• No-see-um
• Midge
• Mosquito