Drain Fly Larvae

Natural Habitat

Found in sludge, slime, or organic matter buildup inside drains, grease traps, septic tanks, and moist soil.

Diet & Feeding

Larvae feed on the organic slime (biofilm), fungi, bacteria, and algae that accumulate in sewage and drain pipes.

Behavior Patterns

The larvae develop within the gelatinous film of drains. They are subaquatic, breathing through a small tube that breaks the surface of the slime. They eventually pupate and emerge as fuzzy, moth-like adult flies.

Risks & Benefits

Generally harmless to humans and do not bite. They act as decomposers by breaking down organic matter in drains. They can be a nuisance in large numbers and may carry bacteria from the sewage they live in to surface areas.

Identified on: 4/15/2026