Flies are insects of the order Diptera, the name being derived from the Greek δι- di- "two", and πτερόν pteron "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advanced mechanosensory organs known as halteres, which act as high-speed sensors of rotational movement and allow dipterans to perform advanced aerobatics. Diptera is a large order containing an estimated 1,000,000 species including horse-flies, crane flies, hoverflies, mosquitoes and others, although only about 125,000 species have been described.
The Tachinidae are a large and variable family of true flies within the insect order Diptera, with more than 8,200 known species and many more to be discovered. Over 1,300 species have been described in North America alone. Insects in this family commonly are called tachinid flies or simply tachinids. As far as is known, they all are protelean parasitoids, or occasionally parasites, of arthropods, usually other insects. The family is known from many habitats in all zoogeographical regions and is especially diverse in South America.
The Bombyliidae are a family of flies, commonly known as bee flies. Adults generally feed on nectar and pollen, some being important pollinators. Larvae are mostly parasitoids of other insects.
Botflies, also known as warble flies, heel flies, and gadflies, are a family of flies known as the Oestridae. Their larvae are internal parasites of mammals, some species growing in the host's flesh and others within the gut. Dermatobia hominis is the only species of botfly known to parasitize humans routinely, though other species of flies cause myiasis in humans.
Horse-flies and deer flies are true flies in the family Tabanidae in the insect order Diptera. The adults are often large and agile in flight. Only female horseflies bite land vertebrates, including humans, to obtain blood. They prefer to fly in sunlight, avoiding dark and shady areas, and are inactive at night. They are found all over the world except for some islands and the polar regions. Both horse-flies and botflies (Oestridae) are sometimes referred to as gadflies.
The Phoridae are a family of small, hump-backed flies resembling fruit flies. Phorid flies can often be identified by their escape habit of running rapidly across a surface rather than taking to the wing. This behaviour is a source of one of their alternate names, scuttle fly. Another vernacular name, coffin fly, refers to Conicera tibialis. About 4,000 species are known in 230 genera. The most well-known species is cosmopolitan Megaselia scalaris. At 0.4 mm in length, the world's smallest fly is the phorid Euryplatea nanaknihali.
The Asilidae are the robber fly family, also called assassin flies. They are powerfully built, bristly flies with a short, stout proboscis enclosing the sharp, sucking hypopharynx. The name "robber flies" reflects their expert predatory habits; they feed mainly or exclusively on other insects and, as a rule, they wait in ambush and catch their prey in flight.
The Acroceridae are a small family of odd-looking flies. They have a hump-backed appearance with a strikingly small head, generally with a long proboscis for accessing nectar. They are rare and not widely known. The most frequently applied common names are small-headed flies or hunch-back flies. Many are bee or wasp mimics. Because they are parasitoids of spiders, they also are sometimes known as spider flies.
Sphaeroceroidea is a superfamily of flies. It includes the cosmopolitan families of Sphaeroceridae, Heleomyzidae, and Chyromyidae, as well as a few smaller groups. It has about 2,600 species.
The Lauxanioidea are a superfamily of flies that includes the two large families, the Lauxaniidae and Chamaemyiidae, and the small family Celyphidae. Generally, they are small to medium, densely populated, coloured flies. The Chamaemyiidae live as parasites on insects. The family Celyphidae look like beetles.
The Heleomyzidae is a small family of true flies in the insect order Diptera. Over 740 described species of Heleomyzidae occur in about 76 genera distributed throughout the world.
The Empidoidea are a large monophyletic superfamily of true flies, the sister taxon to the Muscomorpha (Cyclorrhapha). These two groups are sometimes united in the unranked taxon Eremoneura. There are some 10,000 known species within Empidoidea, which are represented on all continents except Antarctica. They are known to have existed since the Jurassic period.
Dolichopodidae, the long-legged flies, are a large, cosmopolitan family of true flies with more than 7,000 described species in about 230 genera. The genus Dolichopus is the most speciose, with some 600 species.
Empididae is a family of flies with over 3,000 described species occurring worldwide in all the biogeographic realms but the majority are found in the Holarctic. They are mainly predatory flies like most of their relatives in the Empidoidea, and exhibit a wide range of forms but are generally small to medium-sized, non-metallic and rather bristly.
Milichiidae are a family of flies. Most species are very small and dark. Details of their biology have not yet been properly studied, but they are best known as kleptoparasites of predatory invertebrates, and accordingly are commonly known as freeloader flies or jackal flies. However, because of the conditions under which many species breed out, they also are known as filth flies.
An artificial fly or fly lure is a type of fishing lure, usually used in the sport of fly fishing. In general, artificial flies are an imitation of aquatic insects that are natural food of the target fish species the fly fishers try to catch. Artificial flies are constructed by fly tying, in which furs, feathers, thread or any of very many other materials are tied onto a fish hook.
Aulacigastridae is a very small family of flies known as sap flies. The family Stenomicridae used to be included within this family, but was moved by Papp in 1984. They are found in all the Ecoregions.
The Chloropidae are a family of flies commonly known as frit flies or grass flies. About 2000 described species are in over 160 genera distributed worldwide. These are usually very small flies, yellow or black and appearing shiny due to the virtual absence of any hairs. The majority of the larvae are phytophagous, mainly on grasses, and can be major pests of cereals. However, parasitic and predatory species are known. A few species are kleptoparasites. Some species in the genera Hippelates and Siphunculina are called eye gnats or eye flies for their habit of being attracted to eyes. They feed on lachrymal secretions and other body fluids of various animals, including humans, and are of medical significance.
The Inbiomyiidae are a family of flies first described in 2006. 11 species have been described all in the genus Inbiomyia distributed in the Neotropical region. These are very small, mostly dark flies. The larval biology remains unknown.
Natalimyza is a genus of flies placed in the family Natalimyzidae and known as African grass flies. There are about 30 species in Africa which are found mainly in grasslands where their larvae are thought to feed on decaying plant material. They are small yellow to brown and appear like flies in the families Chyromyidae or Opomyzidae, but differentiated by bristles on the head, having four fronto-orbital bristles.
