drain fly

Drain fly (Psychoda phalaenoides). Photo: Joseph Berger, Bugwood.org

Updated: July 17, 2023

About drain flies

  • Drain flies are found primarily in rooms or areas where there are drains - kitchens, bathrooms, and basements near floor drains, etc.

  • Drain flies are small, 1/16 to 1/4 inch long, delicate, and fuzzy. They are pale brownish-gray to black. The larvae live in the gelatinous film or slime in drains and traps. They feed on algae, bacteria, and fungi in the slime.

  • They may also breed in areas of sewer leaks and back-ups, dirty garbage cans, saucers under potted plants, clogged storm drains, and in condensate pans under refrigerators and air conditioners.

  • Adult flies may live up to 2 weeks and total development time from egg to adult may take 7 to 28 days.

  • Flies emerge daily once an infestation is underway.

  • Fungus gnats can also breed in drains. 

small dark fly found near drains and moist areas - drain fly
Drain fly. Photo: Matt Bertone, NC State University


  • Clean traps and drains mechanically or with an over-the-counter drain cleaner followed by hot water. Clean or eliminate breeding sites. 

Rev. 2020

Additional resource

Drain Fly | Northeastern IPM Center