How to Identify and Get Rid of Fungus Gnats
Do you have little flies on your houseplants? They may be fungus gnats! Often considered only a minor houseplant pest, fungus gnats can quickly become a significant issue (and annoyance) if an infestation gets out of hand. Here’s how to identify, eliminate, and prevent fungus gnat infestations in your plants.
What are Fungus Gnats?
Fungus gnats are a fruit fly–sized insect pest that primarily affects indoor houseplants. Attracted to the moisture of potting soil, adult gnats lay their eggs (up to about 200) on organic matter near the soil surface. After about 3 days, the eggs hatch into larvae, which burrow into the soil to feed on fungi and decaying plant material. Adult gnats emerge from the soil 2 weeks later to repeat the process. Adults live for about 1 week.
Fungus gnats are utterly harmless to humans since they can’t bite and don’t spread diseases. However, they can be a problem for houseplants; when the gnats’ population explodes, the larvae feed on plants’ thin roots. Fungus gnats may also spread Pythium, a group of plant pathogens that causes “damping off” in seedlings.
Once you have a fungus gnat infestation, consistent management and prevention techniques are the key to ending it. Further down on this page, we’ve listed a few of the best ways to get rid of adult gnats and prevent new gnats from emerging.