Adults are delicate flies with long, slender legs. They often stand with their antennae curled back over their head. Larvae have two projecting anal spiracles (small tubes) relatively close together at their rear ends.
Metamorphosis is complete. Eggs are orangish, oval, and only about 0.12 inch (3 mm) long. Larvae develop through three instars, are pale yellow to red or brown, and at maturity are about 2.5 mm (1/10 inch) long. Pupae are orange to brown, about 2 mm (1/12 inch) long, and occur beneath plants in litter where they may form cocoons made from soil particles, excrement, and aphid cast skins.