Drain flies — also called moth flies — are the small fuzzy moth-like flies that appear around bathroom and kitchen drains in Chicago apartments and restaurants. They breed in the organic slime that builds up inside drain pipes, so they're a sign of an underlying drain-maintenance issue.
What Do Drain Flies Look Like?
Adult drain flies are 1/8 inch long, dark gray to tan, with fuzzy moth-like bodies and broad rounded wings held tent-like over the body when at rest. They hop or make short fluttering flights rather than sustained flight.
Where Do Drain Flies Hide?
Drain flies breed in the slime layer inside drain pipes, P-traps, and sewer access points. In Chicago that includes bathroom sinks, shower drains, kitchen sinks, floor drains in basements, and commercial kitchen drains. They rest on walls and ceilings near drains during the day.
Signs of a Drain Fly Infestation
Small fuzzy moth-like flies hovering around bathroom or kitchen drains, flies resting on tile walls near drains, and a noticeable increase after a drain has gone unused for a few days (vacation, vacant unit).
Health Risks of Drain Flies
Drain flies don't bite or transmit significant disease, but they're a nuisance and a strong indicator of unsanitary drain conditions. In Chicago commercial kitchens they're a recurring food-inspection issue.
How Sleep Tight Treats Drain Flies in Chicago
Sleep Tight treats drain flies by identifying every affected drain with a tape test, applying a professional-grade bio-foam that breaks down the organic slime layer where larvae develop, and treating cracks and crevices nearby. Bleach alone doesn't work — it doesn't remove the biofilm.
Need help with drain flies in Chicago?
Sleep Tight Pest Control offers same-day chicago general pest control across every Chicago neighborhood and suburb. Call (773) 240-5932 or get a free quote online.
Frequently Asked Questions
How do I tell drain flies from fruit flies?
Drain flies are fuzzy and moth-like with broad wings held tent-like over the body. Fruit flies are smooth, tan, with red eyes and a humped back.
Will bleach down the drain kill drain flies?
No — bleach kills surface bacteria but doesn't break down the organic slime layer where drain fly larvae live. You need a foaming enzymatic product, which Sleep Tight applies.
Why do drain flies come back after I clean the drain?
If even a small piece of biofilm remains, the larvae continue developing. Professional bio-foam treatment fully coats the inside of the pipe where surface cleaning can't reach.
How long does treatment take?
Most drain fly jobs in Chicago are clear within 7–14 days after a professional foam treatment of every affected drain.