
Fungus Gnat. Credit CSU Extension Service
Houseplants, especially ones that we keep outdoors in the warm season and bring back inside when frosts threaten, are likely to harbor Fungus Gnats. These tiny black flying insects (about the size of a fruit fly) can be very annoying but are mostly harmless. Adults lay 75 to 200 eggs that hatch in a week in the top 1” of soil, and when the larvae hatch, they survive mostly on soil fungi, but also feed on tender root hairs. This life cycle lasts about five weeks, although the adults only live about five days. One plant infested with fungus gnats will easily and rapidly spread the insects to nearby plants. [Read More]