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Fungus Gnat Biology

Both adult and larval fungus gnats inhabit humid and dark areas. Adults live for approximately one week, during which time females are capable of laying between 100 and 150 eggs. Eggs hatch within four days and fungus gnat larvae emerge.

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 plant but eventually feed upon the stem 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.

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 advisable. Contact your pest control professional to discuss eradication of indoor populations. 

Fungus Gnats

Fungus Gnat Larvae

Gnats in the Soil