Fungus Gnat

Characteristics

They're somewhat of a magician. If it's a very moist day and there are a lot of gnats out and about, larvae can leave charming little slime trails, just like snails or slugs. They can also pull off a few other magic acts; on mushroom farms they can multiply right before your very eyes. Larvae have elongated, legless bodies.

Where found

Common throughout the U.S.

Habitat

They love any place damp or anything growing, such as potted plants. They often rest on growing plants and even litter. They are attracted to light, so don't be surprised if you find them all over your windows.

Homes and offices are big target areas, as they are full of moisture sources — potted plants, under appliances, in crawl spaces or beneath slabs, and moisture-damaged walls. Of course there's plenty more water outside, too. Large quantities of decaying vegetable matter in damp soil – let's say a vegetable garden – are pretty much begging for an infestation, and gnats are not ones to disappoint.

Food

A rotten diet — who said fresh is best? The name comes from what the larvae eat – they chow down on fungi and decaying matter. Other larvae mostly stick to the decaying plants, animal excrement, or fungus, but some feed on rotting wood or bark of fallen trees.

Biology

All-natural birthers. Not only do gnats love moisture for their food, they love it for laying their eggs. Moist organics or potting soils are perfect birthing grounds. It takes only about 2 weeks from egg to adult.

Damage

Basically just a nuisance in offices, institutions, and homes – though the fungi suffer too.

Invasion

They get through plain old screens and into your home, then breed somewhere moist.

Good riddance

Controlling these insects depends on finding and eliminating its breeding sites. So go throw out all your potted plants right now. (Just kidding). But do inspect them. This fly requires high humidity levels, so stake out areas with high moisture content. Leaks in wall areas or over-watered potted plants are good bets. This is a nuisance pest, so pesticides alone will not get rid of the problem. A good method is drying out moist areas or over-watered house plants. Using aerosol pesticides to kill flying adults will only provide short-term relief, though it can be useful in knocking down populations of adults while you follow the above recommendations. As previously stated, you have to find and eliminate the source to achieve long-term control. When using any pesticide, be sure it is registered for the target pest/location. Read the entire label prior to use. Follow all label directions, restrictions and precautions.