Fungus Gnats in Houseplants: Soil Moisture Management Is Key

Many houseplants (ivy, peace lily, spider plant, morning glory seedlings) have tiny black flies emerging from soil when pots are tapped. Roots washed, no larvae found; repotted but pests persist. Plants stay damp even with biweekly watering (hydroponic mix).

Expert Answer: These are fungus gnats (drawing). Larvae feed on roots, reducing vigor and water uptake. Usually caused by overly wet soil. Let soil surface dry completely between waterings.

— Jack DeAngelis