Eliminating Fungus Gnats: Identification, Treatment, and Prevention

Those tiny, fruit-fly-like insects hovering around your plants are fungus gnats. Adults are a nuisance but harmless; the real problem is their larvae feeding on decaying organic matter in the topsoil. Here's a step-by-step eradication plan:

Immediate Controls

• Dry the soil: Let the top layer dry thoroughly between waterings.
• Surface barriers: Apply a ¼-inch layer of coarse coir, sand, or diatomaceous earth—sharp edges deter larvae.
• Potato traps: Place ½-inch raw potato slices on the soil; discard after 24 hours with larvae inside. Repeat until clear.
• Adult traps: A glass of red wine (cooking wine works) attracts and drowns flying adults.

For Severe Infestations

Use a biological control like Knock-Out Gnats (Gardens Alive) containing beneficial nematodes or Bti.

Prevention Is Key

• Use sterile, bark-free potting mix with ample perlite for drainage.
• Avoid overwatering—the #1 cause of fungus gnats.
• Inspect new plants before bringing them home.

Detection tip: Water lightly and watch the surface for tiny swimming larvae. Good light and sharp eyes reveal them.