Fungus Gnat vs Mosquito
Fungus Gnats and mosquitoes 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 fungus gnat has delicate dark body with long legs and antennae, while a mosquito has long, needle-like mouthpart (proboscis).
Side-by-side comparison
| Fungus Gnat | Mosquito | |
|---|---|---|
| Group | Flies & Mosquitoes | Flies & Mosquitoes |
| Scientific name | Bradysia spp. | Culicidae (e.g. Aedes albopictus) |
| Size | 2–4 mm | 3–6 mm |
| Colors | Black and Gray | Black, White and Gray |
| Legs | 6 legs | 6 legs |
| Wings | Yes | Yes |
| Bites or stings | No | Bites |
| Risk | Nuisance | Health risk |
| Key feature | Delicate dark body with long legs and antennae | Long, needle-like mouthpart (proboscis) |
Key differences
- Size: Mosquitoes are larger, reaching 6 mm, while fungus gnats top out around 4 mm.
- Color: Fungus Gnats are black and gray; mosquitoes are black, white and gray.
- Risk: the fungus gnat is a nuisance pest but not a health threat to most people, while the mosquito can cause medically significant bites, stings or disease.
- Where found: look for fungus gnats indoors; mosquitoes turn up in yards and on patios, near water and in lawns and grass.
- Signature feature: Fungus Gnats: delicate dark body with long legs and antennae. Mosquitoes: long, needle-like mouthpart (proboscis).
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
How to identify mosquitoes
A small, slender fly whose females bite to take blood for egg production. The Asian tiger mosquito is black with white stripes and bites aggressively during the day.
- Long, needle-like mouthpart (proboscis)
- Scales along the wing veins and a slender body
- Asian tiger species has black-and-white striped legs
Which one is more dangerous?
The mosquito carries more risk. Mosquito bites itch and, depending on the region, can transmit West Nile, dengue and other viruses.
Fungus gnats don't bite; larvae can damage seedlings and young roots. Mosquito bites itch and, depending on the region, can transmit West Nile, dengue and other viruses.
Where and when you'll see each
Fungus Gnats turn up indoors, mostly in spring, summer, fall and winter. Mosquitoes turn up in yards and on patios, near water and in lawns and grass, mostly in spring, summer and fall.
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
Fungus Gnats: Let the top inch of potting soil dry out between waterings. Read the full removal guide for more.
Mosquitoes: Dump standing water weekly from pots, gutters, tires and toys. 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 fungus gnats and mosquitoes?
Size: Mosquitoes are larger, reaching 6 mm, while fungus gnats top out around 4 mm.
Which is bigger, a fungus gnat or a mosquito?
Fungus Gnat: 2–4 mm. Mosquito: 3–6 mm.
Do fungus gnats or mosquitoes bite?
Fungus Gnats do not bite. Mosquitoes can bite.
Where are they usually found?
Fungus Gnats: indoors. Mosquitoes: in yards and on patios, near water and in lawns and grass.