Identification
What do fungus gnats look like?
Written by Mustafa Ayan Fact-checked against university extension/IPM sources Last reviewed: October 14, 2026
Direct answer
Adult fungus gnats are tiny (about 1/8 inch), slender, dark gray to black flies with long legs and antennae, shaped like miniature mosquitoes, that fly weakly near houseplant soil. Their larvae are thin, translucent-white worms up to about 1/4 inch long with a shiny black head, found in the top inch or two of damp mix.
Adult fungus gnats
- Size: about 1/8 inch (2–4 mm), smaller than most house flies.
- Color: dark gray to black body, wings clear to lightly smoky.
- Shape: slender, delicate, with long legs and long antennae. Often called "tiny mosquitoes" for that reason.
- Wing detail: a Y-shaped vein pattern is visible under magnification.
- Behavior: weak, erratic flight close to the soil, windows, and lights. They often lift off when you water or move the pot.
Larvae, eggs, and pupae
Larvae are legless, translucent-white to clear, with a distinctive shiny black head capsule. You may see the dark gut through the body. They live in the top inch or two of the mix and sometimes leave faint, slimy trails on the surface.
Eggs are tiny, oval, and pale, laid in the mix and effectively invisible without magnification. Pupae are brief, immobile, and found near the surface. You'll almost never spot them in practice.
To confirm larvae, bury a half-inch cube of raw potato just under the surface for a day or two and check its underside.
Easy to confuse with
- Fruit flies: tan or brown bodies, red eyes, rounder shape. They hang around ripe fruit and drains, not houseplant soil.
- Drain flies: fuzzy, moth-like, with broad hairy wings. They rest on walls near sinks and drains.
- Springtails: wingless, jump instead of flying, and often seen on the soil surface or in a saucer.
- Shore flies: stocky, with pale spots on dark wings, and common around algae-covered soil.
Common questions
What do fungus gnats look like?
Adults are tiny, dark, slender flies with long legs and antennae that resemble miniature mosquitoes. Larvae are translucent white with a shiny black head.
How big are fungus gnats?
Adults are about 1/8 inch long. Larvae reach up to about 1/4 inch.
Are those tiny black flies near my plants fungus gnats?
If they're small, dark, slender, and hover or hop low over the soil (and lift off when you water), very likely yes. Flies clustered at the fruit bowl are probably fruit flies, and fuzzy moth-like flies near drains are drain flies.