Some genera have short, hairy bodies and wings, giving them a "furry" moth-like appearance, hence one of their common names, moth flies.

[4] The larvae of the subfamilies Psychodinae, Sycoracinae and Horaiellinae live in aquatic to semi-terrestrial or sludge-based habitats, including bathroom sinks,[5] where they feed on bacteria and can become problematic.

The larvae of the most commonly encountered species are nearly transparent with a non-retractable black head and can sometimes be seen moving along the moist edges of crevices in shower stalls or bathtubs or submerged in toilet water.

[4][6][7] In small numbers, the larvae are sometimes considered beneficial, as their strong jaws can cut through the hair and sludge waste in drains which might otherwise form clogs.

The adults are half as long as the larvae, but are much broader in appearance, with a pair of hairy wings held pitched-roof-like over the body.

[10] The drain flies which are commonly found in bathrooms, Clogmia albipunctata, are not known to carry any human diseases, but have been known to be an opportunistic agent of myiasis.