Adult : small, dark, fuzzy, moth-like, about 2-3mm long. Adults are weak fliers.

Eggs are laid in filth or grease accumulating on sides of drains and pipes, larvae develop and feed on organic matter and microscopic plants that grow in the filth. Adults emerge after 1-2 weeks.

Adults are often found clinging to walls of damp areas in bathrooms and kitchens. They are weak fliers, flying only a few feet at a time. They do not bite and are usually active at night. They cause annoyance and are perhaps the most common insect inhabitant of sewage treatment plants.