Drain Fly


Actual Size: 1.5 to 5 mm

Characteristics: Small with stocky, hair-covered bodies.

Legs: 6

Wings: Yes

Antennae: Yes

Habitat: Breeds in stagnant water and are often found in drains, sewers, and overflowing gutters.


  • May appear suddenly from sinks and bathtub drains.
  • Get their name from their habit of breeding in drains.
  • Are tiny flies that can easily crawl through normal fly screens.

Drain Flies in Memphis TN Metro Area

Drain flies, also known as moth flies, are members of the Psychodidae family and are named as such because they commonly reproduce in drains. They can be found all across the United States and can become a nuisance in households, occasionally emerging unexpectedly from sinks and bathtub drains. They have the ability to breed in large quantities in sewage treatment facilities and can be carried by the wind to neighboring structures, where they may find their way through fly screens.

Drain Fly Habitat

Drain flies undergo development in decaying matter or gelatinous substances that tend to accumulate in sewage disposal beds, septic tanks, damp compost, or unclean garbage receptacles. They can also emerge from drains in sinks or bathtubs, as well as from tree holes, rain barrels, moisture-rich organic materials, or bird nests with fecal buildup. These flies congregate, mate, and lay their eggs in areas with moisture or stagnant water. They have a particular affinity for the slimy film that forms in sewers and drains, which serves as a favored breeding site. When inside buildings, they are strongly attracted to sources of light and can be found on glass windows, doors, lamps, and indoor lighting fixtures.

Drain Fly Behaviors, Threats, or Dangers

Drain flies pose no threat of biting humans or animals, nor do they cause any structural or plant damage. Nevertheless, since these flies originate from unclean sources, they have the potential to act as mechanical carriers of diseases. Their populations can become bothersome within households, and their presence is typically associated with clogged drains. In residential settings, bathroom drains are the most common breeding grounds for these flies. Due to their limited flying capabilities, drain flies are frequently observed crawling on walls and other surfaces when encountered.

If you are dealing with a drain fly problem in your property, contact your local fly exterminators.