Some species are hairy and have a long, thin abdomen. Biology and developmental times vary between species and because of environmental conditions and availability of food. In general, females lay single white eggs on leaves near aphid infestations or near other suitable food source for that species. Larvae or maggots hatch from eggs in about 3 days. The skin of the last stage larva forms the tan-brown teardrop shaped puparium.
Adults emerge in one to two weeks unless the pupal stage remains through the winter.
Up to seven generations occur annually. Adult flies can be found hovering around flowers, feeding on nectar and pollen. They are often attracted to honeydew covered leaves characteristic of infestations of sucking insects such as aphids. Each larva can consume up to 400 aphids during development. Larvae of other species feed in the nests of ants, termites or bees, and others live in decaying vegetation and wood.