Where to Look for Fungus Gnats
The Next Step in Getting Rid of Them
You are unlikely to spot actual plant damage from the presence of a few fungus gnats, but their appearance alone is enough to make most people to want them gone!
Likely Spots to Find Fungus Gnats
If there are no obvious plants attracting fungus gnats in your home, do a search for any water leaks or damaged material that may be retaining water from a previous leak. These spots could serve as a fungus gnat breeding ground and must be cleaned and repaired to stop the cycle of these pesky insects.
Fungus gnats are also likely to be found in shaded areas near plant matter outside the home, often against the foundation of the building. These tiny insects are able to gain entrance to your home through cracks and other points of entry and so you may spot them inside even if there are no houseplants to be found.
Fungus gnat larvae can be a significant threat to greenhouse-grown flowering plants. The larva's destructive feeding habit leaves the stems and flowers of these plants with injuries that can introduce soil-borne diseases like Pythium and Fusarium. These types of infestations are most common in growing areas where the soil contains a high concentration of peat moss or compost.
How to Spot Dangerous Fungus Gnat Larvae
Fungus gnat larvae are visible to the naked eye and can be spotted with a close inspection of houseplants and other organic matter. Fungus gnat larvae are tiny and worm-like, white or cream in color, with a black head.
One simple test for the presence of gnat larvae in your planting material is to insert a slice of potato into the potting soil. After a day or two, larvae should be visible feeding on the sides of the potato under close inspection. Remove the potato after a few days and move on to learning how to get rid of fungus gnats with the next part of our guide.