Jeff Hahn, University of Minnesota Extension
Description: 1/16 - 1/8 inch long. Slender, dark-colored flies; typically fold wings behind their back when at rest; wings with veins, the middle (median) vein with a conspicuous fork; moderate length antennae.
Where/When: Fungus gnats are found indoors associated with houseplants. They are associated with over-watered soil or in soil with a high content of organic matter. They can be found any time during the year.
Significance: Fungus gnats do not harm people and typically do not harm plants, although they may be considered a nuisance. In rare situations, they may develop inside the walls of buildings where the moisture is high enough to allow fungus to grow.