Fungus Gnat
Treatment Guide
Sciaridae Family · Houseplant Pest Management · Integrated Control
Treatment Strategy
Tap infected pots lightly — gnats will take flight if present. Look for tiny black flies hovering around soil surface and tiny white worm-like larvae on soil surface.
- Adults: 2-8mm black flies, mosquito-like
- Larvae: White/translucent with black heads
- Location: Top 1-2 inches of moist soil
Let the top 1-2 inches of soil dry completely before watering again. The drier the soil mix, the greater reduction in eggs and larvae survival.
Critical: Larvae can't survive in dry soil. This disrupts their lifecycle at the most vulnerable stage and prevents egg-laying females from finding suitable habitat.
Place yellow sticky traps under plant canopy or around pot perimeter. Yellow sticky traps are effective at capturing fungus gnats and provide monitoring of population levels.
Traps last 4-6 weeks unless they fill up with gnats sooner. Position multiple traps for heavily infested plants.
Mix one part hydrogen peroxide (3% strength) to three parts water. Continue using this solution instead of regular water until completely under control.
Hydrogen peroxide kills fungus gnat larvae and soil fungi while oxygenating the growing medium. Safe for most houseplants when properly diluted.
Bacillus thuringiensis israelensis (BTI) is naturally occurring bacterium lethal to fungus gnat larvae. Soak mosquito bits in water for 24 hours to create solution.
BTI disrupts gnats' lifecycle and can eradicate infestations within weeks. Safe for pets, humans, and beneficial insects.
Use sterile potting soil to prevent introducing pests. Ensure containers have drainage holes and avoid decorative planters without drainage.
- Water properly: Allow soil surface to dry
- Remove debris: Dead leaves attract egg-laying
- Quarantine: Isolate new plants for 2 weeks