any member of a family of insects in the fly order, Diptera, that are named for their erratic movements while in flight. Dance flies are small with a disproportionately large thorax and a long tapering abdomen. In males, the abdomen usually bears conspicuous genitalia at the posterior end.

Courtship involves the male presenting a dead fly to the female. Mating does not take place until the female accepts the fly and feeds on it. The adults usually inhabit moist regions and feed on smaller insects. The larvae occur in soil, water, or decaying plant material and also feed on insects.