If you have indoor plants, you probably have at one time or another found the small fungus gnat leisurely flying around one or more of your plants. These dark delicate-looking insects are usually 1/16 to 1/8 inches long with light gray to clear wings. They are weak fliers and are usually visible near the plant or on the soil.
The adult Fungus gnats don’t damage plants. It is the larvae, when present in large numbers that damage roots and stunt plant growth. Fungus gnats can become quite abundant under warm, humid conditions. If you have a severe problem you will need to inspect the area where you are finding them in large numbers. If you are inspecting your plants for these small insects, look for signs of them on the surface of the soil. They will fly up when you water or move your plant. The larvae are white-bodied maggots with black heads about ¼ inch in length, located just under the surface of the soil.
If you don’t have houseplants and find large numbers of Fungus gnats you may need to inspect the area or have a professional check for moisture areas. They may lead you to an area previously undetected by you, such as moist wood, the result of a leak, leading to the growth of fungus.
Fungus gnats are also found outdoors in flowerbeds and landscaped areas that are continuously watered. Letting the soil dry out, raking any mulch and underlying soil thus exposing the moist soil to sunlight and air flow, will dry the soil, killing the fungus which feeds the larvae. You may find that the Fungus gnats are invading your home from outdoors.
If you have indoor plants infested with Fungus gnats, don’t move the plants to a new area or near any other plants not infested with the gnats. Check your plants for signs of overwatering. Allowing the soil to dry may reduce the number of Fungus gnats. You may have to repot the plant or plants. Keep the plants clean of fallen leaves and debris, since Fungus gnats feed on dead plant material.
Some home remedies may work to eliminate the gnats. Sticky traps placed near the infested plant may capture the adult Fungus gnats. If the problem persists you may have to treat with a Pyrethroid insecticide. Be sure the product is labeled for your particular use and follow the label directions.
Houseplants can be an attractive addition to your home. With a little care you can keep them insect free and in healthy condition.