Drain fly (moth fly)

Moist indoor sites, especially bathroom and kitchen drains, sewage pipes, condensate pans, and wet organic sludge.

Larvae feed on bacteria, fungi, algae, and decaying organic matter in drain biofilm. Adults consume little and may take moisture or plant fluids.

Weak, erratic fliers that often rest on walls near plumbing and are most active at night. Eggs and larvae develop in the gelatinous film lining stagnant, damp drains.

They do not bite, sting, or transmit important human diseases, though large infestations indicate unsanitary moisture buildup and may cause minor irritation. Larvae help decompose organic matter, but indoor populations are undesirable.