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Sciarid Flies / Fungus Gnats (Sciaridae)
Sciarid flies, commonly called fungus gnats, are small dark flies whose larvae feed on fungi, algae, and plant roots in moist organic growing media, posing a particular problem in greenhouses, nurseries, and homes with overwatered potted plants. Heavy larval infestations can damage seedlings and young plants by feeding on roots and spreading plant pathogens. Adults are primarily a nuisance but may carry foliar disease spores. Reducing irrigation frequency, applying beneficial nematodes or Bacillus thuringiensis israelensis to the soil, and using yellow sticky traps for adults provides effective management.