PestHelp Guide

Drain Fly

Common in Argentina, South America

Illustration of Drain Fly

About Drain Fly

Drain flies (Psychoda spp.), also called moth flies, are tiny 1.5–5 mm fuzzy flies with leaf-shaped, heavily haired wings that resemble miniature moths. They breed exclusively in the gelatinous biofilm of organic matter coating the inside of drains, sewage pipes, and septic system components. Adults emerge in persistent waves as long as the breeding source is untreated, and can trigger asthma in some individuals. They are a reliable indicator of plumbing buildup or sanitation issues. Enzymatic drain cleaners that break down the biofilm, followed by physical scrubbing, eliminate the breeding source far more effectively than surface sprays.

Geographic Distribution

This insect is found across South America, with notable populations in Argentina and surrounding regions.

Management

If you suspect a Drain Fly problem, consult our recommended exterminator services or browse our full pest species database for related species and control guidance.