Drain fly against a white background - Keep drain flies out of your home with Kona Coast Pest Control in Kailua Kona

Drain Fly

Actual Size: 1.5 to 5 mm

Characteristics: Small in size, featuring broad, fuzzy wings that are covered with small hairs.

Legs: 6

Wings: Yes

Antennae: Yes

Habitat: Live and breed in the vicinity of stagnant water, such as drains, septic tanks, compost, and various other locations.


  • May appear suddenly from sinks and bathtub drains.
  • Get their name from the fact that they often breed in drains.
  • Being tiny flies, they can easily crawl through normal fly screens.
  • Adult drain flies feed on organic matter, algae, and bacteria.

Drain Flies in Kailua Kona

Drain flies, commonly referred to as moth flies, earn their name due to their inclination to reproduce in drains. Widely distributed across the United States, these insects can become a bothersome presence within households, often making unexpected appearances from drains in sinks and bathtubs. Their prolific breeding in sewage treatment plants contributes to their widespread distribution, allowing them to be transported by the wind to neighboring buildings. They can easily pass through standard fly screens, making them a persistent nuisance in residential spaces.

Drain Fly Habitat

Drain flies undergo their development in muck or gelatinous material that gathers in sewage disposal beds, septic tanks, moist compost, or unclean garbage containers. Emerging from drains in sinks or bathtubs, tree holes, rain barrels, moist organic solids, or bird nests with fecal material accumulations is also common. These flies come together, mate, and lay eggs in areas with moisture or standing water, with a particular liking for the slimy film present in sewers and drains as an ideal breeding habitat. Within structures, their affinity for light leads them to congregate on glass windows, doors, lamps, and around indoor lighting.

Drain Fly Behaviors, Threats, or Dangers

Drain flies, while posing no direct threat to humans, animals, or structures, are not entirely harmless. These insects do not bite or cause damage to plants, but their potential as carriers of diseases is a concern. Originating from unclean sources, drain flies can become a nuisance in homes, particularly in association with clogged drains. Commonly breeding in bathroom drains, their weak flying abilities often lead to encounters where they are found crawling on walls and various surfaces. While their presence may not cause physical harm, addressing the root causes of infestations, such as maintaining clean drains, is essential to mitigate their impact on residential environments.

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