Dolichopodidae

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. Dolichopodidae generally are small flies with large, prominent eyes and a metallic cast to their appearance, though there is considerable variation among the species. Most have long legs, though some do not. In many species the males have unusually large genitalia which are taxonomically useful in identifying species. Most adults are predatory on other small animals, though some may scavenge or act as kleptoparasites of spiders or other predators. An expanded concept of the family (Dolichopodidae sensu lato) includes the subfamilies Parathalassiinae and Microphorinae. The latter of these was formerly placed in the Empididae, and was at one time considered a separate family (Microphoridae). However, some authors propose instead that Dolichopodidae s.l. should be known as the epifamily Dolichopodoidae, containing Dolichopodidae, Microphoridae (restored as a family) and the subfamily Parathalassiinae. For clarification of technical terms see Morphology of Diptera Dolichopodidae are a family of flies ranging in size from minute to medium-sized (1mm.-9 mm). They have characteristically long and slender legs, though their leg length is not as striking as in families such as the Tipulidae. Their posture often is stilt-like standing high on their legs, with the body almost erect. In colour most species have a green-to-blue metallic lustre, but various other species are dull yellow, brown or black. The frons in both sexes is broad. The eyes are separated on the frons of males, except in some species of Diaphorus and Chrysotus in which eyes touch above the antennal insertion. On the heads of most species the ocellar bristles and outer vertical bristles are well developed. The face of some species is entire; in others it is divided into two sections: the epistoma and the clypeus. The largest antennal segment is the third; in most species it bears a long arista, which is apical in some species, dorsal in others. In most species the mouthparts are short and have a wide aperture as an adaptation for sucking small prey. The legs are gracile and the tibiae usually bear long bristles. In some genera the legs are raptorial. In some species the tibiae of the males have modifications. The wings of most species are clear or tinged, but some species have wings that are patterned in strong colours or with distinct spots. There are three radial veins (R1, R2+3, R4+5). The medial vein M1+2 is simple or rarely furcate, as in the genus Sciapus. The anterior cross-vein is in the basal part of the wing. The posterior basal wing cell and the discoidal wing cell are always fused. The anal cell of the wing is always small. There are two veins branching from cross-vein DM-Cu in the direction of the wing margin; the upper one in some species curves strongly or forks into M1 and M2. R4+5 are simple, and costa ends near or at M1/M1+2, or continues along the wing margin. The point of origin of Rs is at or very close to h.