Pupation of most of the fully aquatic species occurs underwater, the more semiaquatic species may pupate above water. The pupae may swim to the surface before the adult emerges or it may remain on the bottom. Most species are univoltine or multivoltine, but a some are semivoltine. Adults are terrestrial, mostly short lived, and they may or may not feed before mating. Many have mating swarms.
Some species are parthenogenetic.
Eggs are laid in or near the water. Trophic Roles Larvae assume all trophic roles- scrapers, collectors, shredders, and predators are well represented, some are plant miners and parasitoids. Adults may feed little or not at all, or they may be predators of other insects or molluscs, take pollen and nectar, or feed upon the blood of vertebrates. Communities Diptera communities are usually very complex in all types of aquatic systems with many species separated by habitat, habits, season, and trophic role. Chironomids alone usually have over 50 species present at any undisturbed site.