Eliminating Fungus Gnats from 50+ Houseplants

A massive gnat infestation likely came with new plants. The culprit: fungus gnats (larvae in moist soil).

Mosquito dunks (Bti): Float a dunk in water overnight; use that water to irrigate. Bacillus thuringiensis israelensis kills larvae.
Knock Out Gnats: Commercial product from Gardens Alive.
Reduce watering: Let top soil dry between waterings.
Yellow sticky traps: Catch adults.

Repeat treatment to break the life cycle. Avoid home remedies like vinegar traps—they’re less effective.

Perennials: Fungus Gnats in Houseplants: Sticky Traps, Drier Soil, and Nematodes; Fungus Gnat Elimination: Alcohol Drench and Cultural Fixes; Eliminating Fungus Gnats and Other Flying Pests; Tiny Black Flying Gnats: Fungus Gnats from Overwatering or Rotting Produce—Eliminate by Drying Soil; Fungus Gnat Infestation After Repotting: Causes and Cures; Eliminating Fungus Gnats in Cactus Soil; Fungus Gnats Killing Plants: Larvae Control Guide; Eliminating Fungus Gnats in Pothos Soil; Tiny Black Flying Bugs & Mold on Soil: Both from Overwatering; Sedum Division and Transplanting: Controlling Spread and Sharing Excess

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