The fastest useful split
Drain flies are fuzzy; phorid flies are hump-backed and often run before flight.
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 | Phorid fly |
|---|---|---|
| Body | Fuzzy wings | Hump-backed profile |
| Movement | Weak flight | Erratic running |
| Source | Exposed drain film | Concealed decay/leak |
| Escalation | Clean film | Investigate plumbing |
Observe side profile and movement on a counter.
Persistent phorid flies can signal concealed sanitation problems.
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.
Phorid fly
Phoridae
Hump-backed side profile, erratic running and repeated emergence near hidden moist decay or plumbing defects.
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.