Drain FlyIdentification, facts & practical guidance

Drain flies are small, fuzzy moth flies that develop in wet organic buildup. They are different from fruit flies and fungus gnats.

Compiled by the InsectLibrary Team · Updated 2026-09-30 · Editorial policy

Identification and lookalikes

Clogmia albipunctata - Filter Fly(c) Paolo Zucca, some rights reserved (CC BY). https://creativecommons.org/licenses/by/4.0/ Source: https://www.inaturalist.org/observations/404266638

Psychoda alternata - Psychoda alternataContributed by Keith Bayless; Additional contributions by Steve Nanz

Psychoda sigma - Psychoda sigmaContributed by David J. Ferguson

Adults have hairy wings, often held like a small roof, and make short flights near resting surfaces. Check nearby drains, leaks and other wet organic material for a development site.

Why drain flies keep coming back

Killing visible adults does not remove the larvae living in slime or other decaying material. A breeding source may be a neglected drain, a leak or a less visible plumbing problem.

What to do next

Find and physically remove the organic buildup, and correct drainage or leaks. Do not mix cleaning products. If activity continues without an accessible source, have the plumbing or hidden area inspected.

Drain Fly: species profiles

Explore 15 species profiles covered by this guide, with recorded names and available photos.

Filter Fly

Clogmia albipunctata

Psychoda alternata

Psychoda sigma

Lepiseodina conspicua

Setomima nitida

Lepiseodina superba

Psychoda grisescens

Paramormia furcata

Feuerborniella opposita

Maruina lanceolata

Paramormia corniculata

Pericoma signata

Showing 12 of 15 species. Browse all in Diptera →

Sources and further reading

ipm.ucanr.edu - moth or drain flieshttps://ipm.ucanr.edu/home-and-landscape/moth-or-drain-flies/

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