Identification
Drain flies, also known as moth flies, are small insects measuring about 1/8 inch in length. They have fuzzy, moth-like bodies covered in fine hairs, giving them a gray or tan appearance. Their broad, rounded wings are held roof-like over their bodies when at rest. Unlike other flies, they have short legs and slow, erratic flight patterns.
Lifecycle & Reproduction
Drain flies undergo complete metamorphosis, progressing through egg, larva, pupa, and adult stages. Females lay up to 100 eggs in organic matter inside moist drains. Larvae hatch within 48 hours and feed on decaying material and bacteria. The entire lifecycle is completed in 10 to 15 days, allowing for rapid infestations.
Habits, Diet & Behavior
Drain flies thrive in damp, organic-rich environments. They primarily feed on bacteria and decomposing organic matter found in drains, sewage systems, and standing water. While they are weak fliers, they can crawl along surfaces and are most active during the evening hours.
Where You’ll Find Them / Typical Locations
Drain flies are commonly found in:
- Kitchen and bathroom drains
- Sewers and septic tanks
- Sump pumps and clogged pipes
- Moist basements and utility rooms
- Areas with standing water or slow drainage
Threats & Danger
Drain flies do not bite or transmit diseases, but their presence indicates sanitation issues. Large infestations can become a nuisance, especially in kitchens and bathrooms. Their larvae may contribute to clogged drains by feeding on organic buildup.
Prevention
- Clean and flush drains regularly to remove organic buildup
- Fix leaks and improve ventilation to reduce excess moisture
- Use drain covers to prevent flies from accessing breeding sites
- Avoid leaving standing water in sinks, basements, or sump pumps
- Sanitize garbage disposals and sink overflows to eliminate food sources
Signs of Infestation
- Small, fuzzy flies resting near drains, sinks, or showers
- Slow-flying insects appearing near moisture sources
- Larvae visible in drain pipes or organic sludge buildup
- Clusters of flies around damp areas, such as sump pumps
- Increased fly activity in bathrooms and kitchens at night
How to Get Rid of It
- Use enzymatic drain cleaners to break down organic matter
- Flush drains with boiling water or a baking soda and vinegar mixture
- Install drain screens to prevent further infestations
- Apply residual insecticides around drains if necessary
- Seek professional pest control for persistent infestations