Fungus Gnats

Fungus Gnat Control & Identification

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Fungus gnats belong to the families Sciaridae and Fungivoridae and typically are found in and around areas with high humidity. Female fungus gnats deposit their eggs in soil or other damp, decaying organic plant material. These eggs hatch into larvae. The larvae of some species feed on fungus in overwatered soil, but there are other species that consume plant roots as a source of nutrients. This leads to diminished health in affected plants. When infested with fungus gnat larvae, plants show signs of stunted development. Gnat larvae also carry plant pathogens and make plants highly susceptible to various plant diseases.

Unlike some other flying insects, fully mature fungus gnats often remain low to the ground, close to plants and soil. Adults are seen on leaf litter and foliage, while larvae remain in the soil until they pupate. The larvae of fungus gnats are legless and have transparent bodies with black head capsules. Pupae are difficult to see without the use of a magnifying glass. They are stout and dark in color.

Fungus Gnat Life Cycle & Biology

Larvae develop and feed in damp, organic material and are typically found in the soil around potted plants indoors. Larvae begin feeding on fungus or on the root hairs of plants but eventually feed upon the roots of the plant, as well as edible organic material present within the soil. Dark-winged fungus gnat larvae feed on the roots of alfalfa, carnation, clover, corn, cucumbers, Easter lilies, geraniums, lettuce, nasturtium, peppers, poinsettias, potatoes, soybeans, wheat and other organic matter.

Larvae then undergo a pupal stage that spans approximately three days, after which adult gnats emerge. These adult fungus gnats continue the mating cycle, increasing the population of their species. Because fungus gnats are extremely small, their presence can go undetected until previously healthy plants show signs of wilting and disease.

Both adult and larval fungus gnats inhabit humid and dark areas. Eggs hatch within a few days, and fungus gnat larvae emerge.

Controlling or Getting Rid of Fungus Gnats

The use of natural parasites may be effective in commercial growing environments. Fungus gnats infest home, office, commercial and apartment plants, as well, and insecticide use is not effective. Rather, it is important to constantly monitor your houseplants for winged adults. Do not overwater plants. Schedule a pest control inspection to discuss eradication of indoor populations.