Fungus Gnat
Bradysia spp.
low risk
insect
Overview
Tiny flies that breed in moist potting soil. Larvae damage plant roots; adults are nuisance. Major greenhouse pest.
Adults 2-4mm, dark gray with long legs, single pair of wings with Y-shaped vein pattern. Larvae white with black heads.
Prevention Strategies
- •Allow soil to dry between waterings
- •Use well-draining potting mix
- •Sticky yellow traps for adults
- •Cover soil surface with sand or grit
Control Methods
- •Let soil dry out significantly between waterings
- •Yellow sticky traps
- •Bacillus thuringiensis var. israelensis (BTi) soil drench
- •Beneficial nematodes (Steinernema feltiae) drench
- •Hydrogen peroxide 3% soil drench
- •Diatomaceous earth on soil surface
Interesting Facts
- •Adults are completely harmless - larvae cause the damage
- •Overwatering is the #1 cause of fungus gnat infestations
- •Beneficial nematodes are highly effective and completely safe for plants and people
- •Can complete a full generation in 3 weeks in warm conditions