If you notice tiny black flies hovering around your houseplants, you’ve likely got a fungus gnat infestation. While they’re mostly harmless to humans, they can damage plant roots and become incredibly annoying.
The good news? You can get rid of fungus gnats in houseplants naturally — no harsh chemicals needed.
🐛 What Are Fungus Gnats?
Fungus gnats are small, mosquito-like flying insects that thrive in moist soil. Adult females lay eggs in the topsoil, and the larvae feed on organic matter and sometimes delicate plant roots.
Signs you have fungus gnats:
- Small black flies swarming around the plant or soil
- Larvae (tiny white worms) in the topsoil
- Wilting or yellowing leaves due to root damage
- Sudden drop in plant health despite normal care
🌿 Natural Ways to Get Rid of Fungus Gnats in Houseplants
1. Let the Soil Dry Out
Fungus gnat larvae thrive in wet soil. Letting the top 1–2 inches dry out between waterings breaks their life cycle and prevents new eggs from hatching.
2. Bottom Water Your Plants
Instead of watering from the top, place water in the saucer below. This keeps the topsoil dry — making it harder for gnats to lay eggs.
3. Add a Layer of Sand or Gravel
Cover the top of the soil with a thin layer of coarse sand or decorative gravel. It physically blocks gnats from reaching the soil to lay eggs.
4. Use Yellow Sticky Traps
These traps are inexpensive and available at most garden centers. Place them near affected plants to catch adult gnats and reduce their numbers quickly.
👉 Example product on Gardener’s Supply
5. Neem Oil Spray
Neem oil acts as a natural insect growth regulator. Mix:1 tsp neem oil + 1/2 tsp dish soap + 1 liter of water
Spray the solution on leaves and soil every 3 days for 2 weeks.
6. Try Hydrogen Peroxide Solution
Mix 1 part 3% hydrogen peroxide + 4 parts water. Water your plant once with this solution to kill larvae in the soil. It breaks down into oxygen and water — safe for plants when used correctly.
👉 More from the EPA on hydrogen peroxide safety
❌ What NOT to Do When Dealing with Fungus Gnats
- Don’t overwater — moist soil is gnat heaven
- Avoid harsh vinegar or alcohol sprays — they can harm roots
- Don’t ignore the issue — gnats reproduce rapidly
🌱 How to Prevent Fungus Gnats in Houseplants
- Always inspect new plants before bringing them inside
- Quarantine new additions for a few days
- Sterilize reused pots and tools
- Use clean, pest-free potting soil
- Maintain moderate watering habits and monitor moisture
🧪 Extra Tip: Use Mosquito Bits for Long-Term Fungus Gnat Control
Another highly effective method to get rid of fungus gnats in houseplants is using Mosquito Bits (a biological larvicide).
These granules contain Bacillus thuringiensis israelensis (BTI), a natural bacterium that targets fungus gnat larvae in the soil. Simply soak 1 tablespoon of Mosquito Bits in a gallon of water for 30 minutes, then use it to water your plants.
✅ It’s safe for most houseplants and non-toxic to people and pets.
🧼 Clean Your Space Too
Fungus gnats are drawn to moisture and decaying organic matter, not just your plants.
- Empty plant saucers of excess water
- Clean up fallen leaves or spilled soil
- Avoid keeping organic trash (like banana peels) near your plant shelf
A clean environment helps you eliminate gnats faster and prevent reinfestation.
🤔 FAQ: Fungus Gnats & Houseplants
How long does it take to get rid of fungus gnats in houseplants?
With consistent treatment, most infestations clear in 1–2 weeks.
Are fungus gnats harmful to humans?
No. They don’t bite or sting, but they’re annoying and harmful to plants.
Do sticky traps stop gnats completely?
No, but they help control adult populations. You still need to treat the soil.
Is neem oil safe for all plants?
Most houseplants tolerate neem well, but test on a small area first.
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