1/5 to 1/6 inch long, tan colored body, black and white wings. Body and wings are covered with hair. The wings appear larger than their bodies and are blamed for their weak flying ability. Antennae have 13 segments with the last being a bulb-like shape.
Eggs are laid in masses numbering 10-200 on the gel-like film that covers filters, drains, pipes or sewage disposal beds. Larvae emerges 32 to 48 hours later. They are gray, legless, 3/8 inch long, and live in the film breathing through a tube. This continues for 9 to 15 days then pupae float to the surface. Adults emerge after 20 to 40 hours. Adults live about 14 days.
They are possibly the most common insects living in sewage plants.
Occasional problems in homes, usually emerging from sink drains especially in the spring.