The fastest useful split
Fruit flies center on fermentation; fungus gnats center on moist potting soil and have longer legs.
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 | Fruit fly | Fungus gnat |
|---|---|---|
| Source | Fruit/recycling | Potting soil |
| Body | Compact tan | Slender dark/long legs |
| Flight | Hovers at food | Weak near pots |
| Larva | Fermenting residue | Soil with dark head |
Test fruit sources and each plant pot separately.
Use plant-safe labeled methods only.
Open safety guidanceCheck each full evidence profile
Fruit fly
Drosophilidae
Compact tan flies hovering actively around fermenting fruit, beverage residue or recycling.
Fungus gnat
Sciaridae
Long-legged dark gnats hovering close to moist plant soil, with translucent dark-headed larvae in media.
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.