The fastest useful split
Drain flies look fuzzy and rest near wet film; fruit flies hover around fermentation.
Do not rely on a single color match. Start with scale and physical form, then check where the sign accumulates and whether a companion clue supports one candidate over the other.
| Feature | Drain fly | Fruit fly |
|---|---|---|
| Adult | Fuzzy moth-like wings | Smooth compact tan fly |
| Movement | Weak short flight | Active hovering |
| Source | Drain film | Fruit/sugary residue |
| Test | Emerges from drain | Declines after food removal |
Isolate the suspected source overnight.
Never mix drain chemicals.
Open safety guidanceCheck each full evidence profile
Drain fly
Psychodidae
Fuzzy triangular wings, weak short flight and adults resting near one persistent wet-film source.
Fruit fly
Drosophilidae
Compact tan flies hovering actively around fermenting fruit, beverage residue or recycling.
Why a visual match can fail
Scale can be distorted by a close-up photograph, loose material may be moved by cleaning or airflow, and old evidence can change color or texture. A reliable conclusion uses multiple observations that point in the same direction and preserves contradictory details instead of forcing a match.