Drain Fly

Natural Habitat

Damp environments rich in organic matter such as sink drains, sewers, septic tanks, and wet soil.

Diet & Feeding

Larvae feed on the gelatinous film (biofilm) of algae, fungi, and bacteria in drains; adults primarily consume nectar or polluted water.

Behavior Patterns

Weak fliers that often crawl on walls or surfaces; they are most active at night and are attracted to light. Their life cycle from egg to adult takes about 7 to 28 days.

Risks & Benefits

Generally harmless to humans as they do not bite or transmit diseases; however, they can be a nuisance and may potentially transport surface bacteria from contaminated areas. They help break down organic matter in sewage.

Identified on: 5/28/2026