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Home > Bugs > Bugs of Homes and Structures > Fungus Gnats

Fungus Gnats

Fungus gnats are tiny black flies, frequently numerous in greenhouses and around certain house plants. Often called manure flies or mushroom flies, the adults do not feed on or damage plants. The larvae primarily feed on fungi and organic matter in the soil. Sometimes the maggots also feed on the roots of flower crops, especially poinsettias, geraniums, lilies, African violets and chrysanthemums. Heavy infestations cause plants to wilt, lose vigor, and drop their leaves. Larvae are pests because of the damage they cause to plants; adults are considered pests because they fly about the house in large numbers.

 

fungus gnat maggot fungus gnat adult fungus gnat adult
Larvae of fungus gnats (maggots) are white with shiny black heads and grow to about 1/4 inch in length. Adults are black or brown, slender, about 1/8 inch in length and have one pair of delicate, clear wings. The adults are often confused with mosquitoes because of their long, slender dangling legs.

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Identification and Control Information (each will open in a new window)

 

 

[Photos, left to right: David Cappaert, Michigan State University, Bugwood.org; Whitney Cranshaw, Colorado State University, Bugwood.org; David Cappaert, Michigan State University, Bugwood.org]

 
It is the policy of the State of Maine to minimize reliance on pesticides. The Maine Department of Agriculture and the Maine IPM Council encourage everyone to practice integrated pest management and to use pesticides only as a last resort. The mention of pesticides in the fact sheets linked to these pages does not imply an endorsement of any product. Be sure that any product used is currently registered and follow all label directions.