Identification

• Fungus gnats (Bradysia species) are 1/8-inch gray or black gnats that resemble small flies. They fly around houseplants and scurry across soil when you water. Attracted to light, they also collect on windows. Fungus gnat larvae live in the soil and are 1/4 inch long and white with shiny, black heads.
  
  

Damage

• Adult fungus gnats are simply pests, but their larvae feed on organic matter in the soil, including plant roots and crowns. Seedlings and young plants can be fatally damaged by larval feeding, while mature plants can become stunted with off-color leaves. Severely infested plants drop foliage.
  
  

Management

• Fungus gnats thrive in moist soil. The larvae die if you allow the first 2 to 3 inches of soil to dry between waterings. Adult larvae can also be caught on yellow sticky cards, which may prevent them from breeding and continuing the cycle.