Flies Order Diptera

Identification: One pair of membranous wings, borne by meso-thorax (wings rarely reduced or lacking). HW reduced to small knobbed structures (halteres). Antennae variable, often short, inconspicuous, and ^-segmented. Compound eyes large, sometimes meeting on dorsal side of head. Mouth parts sucking (rarely vestigial), maxillary palps well developed, labial palps lacking. Tarsi nearly always 5-segmented. Relatively soft-bodied. Metamorphosis complete.

Similar orders: Most insects in other orders likely to be confused with Diptera have 2 pairs of wings. The few with 1 pair (certain grasshoppers, beetles, mayflies, and others) generally do not resemble flies. Male scale insects resemble midges, but have 1-segmented tarsi and 1 or 2 long stylelike processes at end of the abdomen.

Immature stages: Larvae are usually legless and wormlike, and often lack a well-developed head; they are commonly called maggots. They live in water, soil, decaying materials, or in plant or animal tissues. Many are aquatic and occur in a variety of aquatic habitats. The plant-feeding species generally live in the roots, fruit, leaves, or other parts of the plant. Many are parasitic, living in the bodies of other animals.

Habits: Flies occur in many different habitats; each species is usually found near the habitat of its larvae. Adults often occur on flowers. Many are bloodsucking, and are to be found on or near the animals on which they feed.

Importance: Flies constitute one of the larger orders of insects and are abundant in individuals as well as species; they occur almost everywhere. They are an important food of many larger animals. Many species are parasitic or predaceous on other insects and are of value in keeping noxious species under control; others are of value as scavengers. Large numbers are a nuisance because they bite; some are important as vectors of disease. Many attack and damage cultivated plants; a few of these serve as vectors of plant diseases.

Classification: Three suborders — Nematocera, Brachycera, and Cyclorrhapha — differing principally in wing venation and an-tennal structure. Wing venation provides useful characters for separating families throughout the order; the venational terminology usually used is that of Comstock, but many terms of an older terminology, particularly those referring to cells, are frequently used; these 2 terminologies are illustrated opposite. Other characters used in separating families of Diptera are discussed in the accounts of the groups in which they are used. No. of species: World, 87,000; N. America, 16,144.

Wing of Horse Fly showing venational terminologies

4th posterior old cross vein System

Wing of Horse Fly showing venational terminologies

4th posterior old cross vein System

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