True flies

Code QD999999

See Key to Families of Australian Aquatic Diptera Larvae

The Diptera is a major order in which aquatic larvae are typical of many Nematocera, with over 10,000 aquatic species in several families, including the speciose Chironomidae (non-biting midges), Ceratopogonidae (biting midges), Culicidae (mosquitoes) and Simuliidae (black flies). Holometabolous; adults terrestrial, aerial.

Larva are commonly vermiform, diagnostically with unsegmented prolegs, variably distributed on body; primitively with sclerotised head and horizontally operating mandibles, in more derived groups the head is progressively reduced, ultimately (in the maggot) with head and mouthparts atrophied to cephalopharyngeal skeleton; open (amphi- or meta-, rarely propneustic) or closed tracheal systems, gaseous exchange cuticular, through spiracular gills or terminal, elongate respiratory siphon with spiracular connection to atmosphere. Three or 4 (black flies up to 10) larval instars; pupation predominantly subaquatic: pupa non-mandibulate, with appendages fused to body; puparium formed in derived groups (few of which are aquatic) from the tanned retained third-instar larval cuticle. Emergence at the water surface may involve use of the cast exuviae as a platform (Chironomidae and Culicidae), or through the adult rising to the surface in a bubble of air secreted within the pupa (Simuliidae).

Development varies from 10 days to greater than one year, with many multivoltine species; adults may be ephemeral to long-lived. At least some dipteran species occur in virtually every aquatic habitat from the marine coast, salt lagoons, sulphurous springs, to fresh and stagnant waterbodies, from temporary containers to rivers and lakes; temperatures tolerated range from 0oC for some species to 55oC in thermal pools for a few others.