Treatments
Fungus gnat treatment, side by side
Written by Mustafa Ayan Fact-checked against university extension/IPM sources Last reviewed: October 14, 2026
Direct answer
No single treatment ends a fungus gnat infestation, because each method reaches a different life stage. Drying the mix and Bti target eggs and larvae, while sticky traps catch adults. Combine moisture control and traps, add Bti if needed, then keep monitoring for several weeks.
Each method below reaches a different stage of the life cycle. The full guide explains how to stack them; each card links to complete, step-by-step instructions.
Most important · Ongoing
Let the soil dry
Fungus gnats breed in constantly wet mix. Let the top 1–2 inches dry between waterings and you remove their nursery.
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Adults · 5 minutes
Yellow sticky traps
Place yellow cards at the soil surface to catch egg-laying adults. Traps monitor the infestation — they do not finish it alone.
Read the guide
Best-supported larvicide · Per product label
Bti (Mosquito Bits)
Bacillus thuringiensis israelensis is a bacterium that specifically targets fly larvae. Use a product labeled for fungus gnats and follow its rate and reapplication instructions.
Read the guide
Optional — use cautiously · 10 minutes
Hydrogen peroxide drench
A diluted peroxide drench is a common household suggestion, but extension guidance on it is mixed. Not part of the default plan — read the cautions before using it.
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Keep them gone · Habit change
Prevention that actually sticks
Bottom watering, a sand or grit top-dress, sterile mix, and empty cachepots. Keep monitoring for a couple of weeks after adults stop appearing.
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Not sure where to start?
Start with identification, then find the likely breeding source, then manage moisture for that specific plant, then monitor with sticky traps — that alone resolves many light cases. Add a labeled Bti product if moisture control and traps aren't enough on their own, and troubleshoot if activity doesn't decline. The 7-Day Starter Plan turns that into a day-by-day checklist.