How to get rid of gnats
What people call 'gnats' is usually one of three things — fungus gnats (potted plants), drain flies (drains and biofilm), or fruit flies (food). Each has a different fix. Identify which you have and treatment becomes simple.
Tools
- ✓For diagnosing overwatered houseplants — the root cause of fungus gnats.
Materials
- +Stake into houseplant soil. Catches adult fungus gnats and shows you which plants are infested.
- +Sprinkle on top of houseplant soil OR steep in watering can. BTI kills fungus gnat larvae in the soil.
- +Mix per label with water and a drop of soap. Soil drench kills larvae and discourages adults.
- +Mix 1 part H2O2 to 4 parts water. Water plants with it once — kills larvae in soil without harming the plant.
- +Enzyme-based. For drain gnats.
Steps
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1
Identify which gnat you have
Around houseplants and in soil = fungus gnats. Around sinks and showers, weak fliers = drain flies. Around fruit bowls and trash = fruit flies (see that guide). Treatment is completely different — guess wrong and nothing works.
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2
For fungus gnats: let the soil dry out
Fungus gnats need damp soil to breed. Let the top inch dry between waterings. Stop bottom-watering plants for the next 3 weeks.
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3
Stake yellow sticky traps in every pot
Catches adults so they can't lay more eggs. The card also tells you which plants are infested — you'll see clusters on the worst pots.
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4
Water with BTI or H2O2 solution
Either: steep Mosquito Bits in your watering can for 30 minutes, then water normally. OR: water with 1:4 hydrogen peroxide:water once. Both kill larvae without harming the plant. Repeat at 1 week.
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5
For drain flies: enzyme treatment
Pour Bio-Clean down drains at bedtime for 3 consecutive nights. Cover the drain with a piece of clear tape overnight to confirm — flies stuck to the tape in the morning confirms drain breeding.