Fruit Fly vs Fungus Gnat
Fruit Flies and fungus gnats are easy to mix up at a glance, but a few details separate them quickly. Here is how to tell which one you found and what, if anything, you should do about it.
Quick answer
Check for this first. A fruit fly has very small tan body with bright red eyes, while a fungus gnat has delicate dark body with long legs and antennae.
Side-by-side comparison
| Fruit Fly | Fungus Gnat | |
|---|---|---|
| Group | Flies & Mosquitoes | Flies & Mosquitoes |
| Scientific name | Drosophila melanogaster | Bradysia spp. |
| Size | 2–4 mm | 2–4 mm |
| Colors | Tan, Brown and Red | Black and Gray |
| Legs | 6 legs | 6 legs |
| Wings | Yes | Yes |
| Bites or stings | No | No |
| Risk | Nuisance | Nuisance |
| Key feature | Very small tan body with bright red eyes | Delicate dark body with long legs and antennae |
Key differences
- Color: Fruit Flies are tan, brown and red; fungus gnats are black and gray.
- Where found: look for fruit flies in the kitchen; fungus gnats turn up indoors.
- Signature feature: Fruit Flies: very small tan body with bright red eyes. Fungus Gnats: delicate dark body with long legs and antennae.
How to identify fruit flies
A tiny, tan fly with bright red eyes that hovers over ripe fruit, drains, trash and spilled drinks. It can go from egg to adult in about a week.
- Very small tan body with bright red eyes
- Slow, hovering flight around produce
- Gathers around fermenting fruit, wine and vinegar
How to identify fungus gnats
A tiny, dark, mosquito-like fly that hovers around houseplants and windows. Its larvae live in moist potting soil and feed on fungi and roots.
- Delicate dark body with long legs and antennae
- Weak, erratic flight near plants
- Y-shaped vein pattern in the wings
Which one is more dangerous?
Neither is more dangerous than the other; both are rated nuisance on our scale.
Fruit flies don't bite; they can carry bacteria from trash onto food. Fungus gnats don't bite; larvae can damage seedlings and young roots.
Where and when you'll see each
Fruit Flies turn up in the kitchen, mostly in spring, summer and fall. Fungus Gnats turn up indoors, mostly in spring, summer, fall and winter.
Where you found the bug is itself a strong clue, since these two rarely share the same spots.
What to do if you find one
Fruit Flies: Refrigerate or toss overripe fruit and rinse recyclables. Read the full removal guide for more.
Fungus Gnats: Let the top inch of potting soil dry out between waterings. Read the full removal guide for more.
Biology: flies & mosquitoes
Flies have only one pair of working wings; the second pair is reduced to small balancing knobs called halteres. They go through complete metamorphosis, and the larvae, called maggots, need moist organic material such as garbage, soil, drain film or standing water.
Frequently asked questions
What is the main difference between fruit flies and fungus gnats?
Color: Fruit Flies are tan, brown and red; fungus gnats are black and gray.
Which is bigger, a fruit fly or a fungus gnat?
Fruit Fly: 2–4 mm. Fungus Gnat: 2–4 mm.
Do fruit flies or fungus gnats bite?
Fruit Flies do not bite. Fungus Gnats do not bite.
Where are they usually found?
Fruit Flies: in the kitchen. Fungus Gnats: indoors.