Drain Fly (also known as Moth Fly, Sink Fly, or Sewer Gnat)
Scientific Name: Clogmia albipunctata (most common species) or Psychoda spp.
Order & Family: Order: Diptera (True Flies), Family: Psychodidae
Size: 1.5 to 5 millimeters in length
Natural Habitat
Damp environments rich in organic matter, predominantly moist drains, sewer lines, septic tanks, and areas with standing water or decaying vegetation.
Diet & Feeding
Larvae feed on decaying organic matter, sludge, and microscopic organisms (bacteria, algae, fungi) found in drains; adults essentially do not feed or may consume nectar/polluted water.
Behavior Patterns
They are weak fliers that tend to hop or make short, erratic flights. They are nocturnal and are often found resting motionless on walls near sinks, tubs, and showers during the day. Their wings are held roof-like over the body.
Risks & Benefits
Risks: They do not bite or sting but are considered a nuisance pest. They can mechanically transport bacteria from sewers to clean surfaces. Benefits: In natural settings, larvae aid in decomposition; in sewage treatment plants, they can help break down sludge.
Identified on: 2/25/2026