Discover everything you need to know about gnats in our guide below.
What are Gnats?
Gnats are tiny, flying insects known for infesting potting mix, soil, and other organic materials. There are more than 600 different species of gnats in North America, but some of the most common include fungus gnats and dark-winged fungus gnats.
What do Gnats Look Like?
Most species of gnats are very similar in appearance. They have small bodies divided into three parts – the abdomen, head, and thorax. They are usually 1-13mm long, with delicate wings and long, skinny legs.
They have one pair of antennae that are longer than their head and tend to be black, gray, brown, or yellow.
Gnats 101: Behavior, Diet & Habits
Behavior, Diet & Habits
Like many other insects, gnats begin life as eggs. They hatch into larvae and become pupae before reaching maturity. Fungus gnats live for about 18-30 days, and females can lay up to 500 eggs in that time.
Fungus gnats lay their eggs in moist soil or organic matter. When the larvae hatch (about six days after the female lays her eggs), they move directly to nearby plants or decomposition materials, feeding on host plants, mulch, leaves, grass clippings, compost, or anything else they can reach.
The larval stage lasts for about one week, at which point gnats become a pupa. This process takes 3-6 days and precedes the gnats becoming winged, sexually mature adults.
As they mature, gnats feed on plants, fungi, and other organic matter. They’re common in greenhouses, nurseries, and sod farms and tend to stay close to high-moisture areas, like overwatered houseplants.
How to Get Rid of Gnats
The best way to prevent gnats in your house is to keep your indoor plants inside at all times – don’t ever put them outside where they could come into contact with fungus gnats.
You should also be careful to protect the potting soil for your indoor plants – only use potting soil that comes straight from a sealed bag, not one that has been allowed to sit open outside.
Once you have gnats inside, getting rid of them can take time and effort. We recommend starting by eliminating their habitat.
The first step is to remove the moisture sources they rely on. Stop overwatering plants, remove standing water from plant trays, and treat all affected plants with a natural insecticide. We also recommend using beneficial nematodes and other over-the-counter insecticide drenches to control fungus gnat populations. Another way to deter gnats is to add 0.5” of decorative sand on top of the soil in your houseplants. The sand will create a dry environment in which fungus gnats cannot thrive.
Purchase a few store-bought sticky traps to kill remaining adult gnats. To kill gnat eggs and larvae, bleach your drains (or use white vinegar).
For more information on how to get rid of gnats in your home, check out our complete guide.
While gnat bites don’t hurt, people can have adverse reactions to gnat bites. Anaphylaxis is possible, and gnats can transmit infectious diseases via their bites. Additionally, gnats can damage your houseplants and cause an unwelcome pest infestation, so it’s wise to get rid of them promptly.
While gnats and fruit flies are both flying pests, they look different. While fruit flies have round bodies that resemble smaller versions of common house flies, gnats have thinner, more elongated bodies and longer legs, which makes them look like tiny mosquitos. They’re also from different families: the common fruit fly is from the Drosophilae family, while gnats are from various families, including Sciaridae, Anisopodidae, and Mycetophilidae.