How to Control Fungus Gnats on Indoor Plants
Fungus gnats are those little hopping bugs you see when you water your indoor plants. They are 1/32 to 1/50 inches with black or gray bodies and clear wings. Plants grown under cover are most susceptible. The larvae feed on dead roots and leaves, but sometimes consume tender new roots.
- Difficulty:
- Moderately Easy
Instructions
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1
Look for small insects on the surface of the soil. They will be active when you water or move the plant. The larvae are 1/4 inch white-bodied maggots with black heads and can be found just under the surface of the soil.
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2
Keep plants clean of fallen leaves and debris. Fungus gnats feed on dead plant material.
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3
Plant pots of wheat to lure fungus gnats, then compost the soil and the wheat once the female fungus gnats have laid their eggs in the pots. This technique works well in greenhouses or greenhouse windows.
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Use yellow sticky traps placed near the infested plant to catch adult fungus gnats.
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5
Water with a solution of Bacillus thuringiensis, an organic control for caterpillars, to kill insect larvae. Bacillus thuringiensis (or Bt) is a bacteria and is safe to use around children and pets.
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6
Drench the soil with a solution of pyrethrin, an organic pesticide made from chrysanthemums.
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Tips & Warnings
The adults cause no damage to healthy, mature plants but are a nuisance inside the house.
You can make your own sticky traps by spreading tanglefoot onto stiff yellow paper.
Always try the least toxic method of pest control as your first step.
Although Bt is organic and safe to use, it will kill all types of caterpillars, including butterfly larvae. Spray only the plants that are affected.
Never use chemical pesticides inside the house.
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Comments
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Sandra Wieckowski I'm experienced all right. Exprienced at "getting" fungus gnats! HA! But that's about it. The hydrogen proxide method consisted of totally saturating the soil in your potted plants, which supposedly would kill the fungus gnat larvae, and keep repeating every 6-10 days, so as new eggs hatch and became larvae, the proxide would get them. The theory seemed to make sense to me at the time. Of course, I should point out, at that picticular period, I had already entered a level of fungus gnat madness that I didn't know even exsisted. If someone had suggested painting my face like a clown, then stand on my head in a corner three times a day for a week, I would have tried it. In fact, now that I think of it, thats the one thing I didn't try... Who knows?!! The hydrogen proxide didn't work. At that point, what ever I would try seemed to actually create more fungus gnats! Thats when I gave up and hung the plants outside. I had these same plants for over 20 yrs and the house was very empty without them. So this is what I ended up doing. It's been a month, and so far, so good. I took each plant out of its pot and let them soak in a pail of water with B-12 added(one tablespoon B-12 per gallon of water) This helps them not experience as much shock during transplant. Make sure no old soil is on the roots or anywhere on the plant. There could be fungus gnat eggs lurking in the old soil. Although I sterilized my old pots by letting them soak in boiling water, I would suggest buying new pots. Buy high end potting soil. You know, the nice black stuff. When you are putting the new soil in your pot, stop an inch to inch and a half from where you would usually fill it. Go to Home Depot, and buy a bag of play sand(sand-box sand) and top off each pot with an inch to inch and a half with the sand. Pack it good, especially around the stems. This stops the larvae(from the new potting soil) from getting to the surface, and stops adults from laying eggs in your soil. And then hold your breath. That's the best I can tell you Sandra, and I wish you all the good luck!
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Hi. I recently repotted several of my African Violets and now for the first time ever I have these fungus flies all over my plants. One of my beautiful violets is limping and I fear it won't survive. I've had it for years!! What is the hydrogen peroxide method? You sound experienced, what are the best natural methods.?? Please help.
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Can anyone tell me of something I can use from around the house to get rid of these fungus gnats? Have a Sago palm that had moss on the top for decoration and I found 1000's of these pests on the top of the soil. It's getting out of hand is there someone who can help me with this problem?
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The gardening guy at Home Depot told me to put sand on top of the potting soil as this would suffocate them and my problem would be solved. So far a drastic reduction, but I'm leary that this will be a cure all as I still see a few adults flying around.
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Soil sounds too moist and indoor warm temps during summer invites a food source for hungary fungus gnats -they feed on plant debris, fungus and algea. Changing your watering habits could prove helpful. Letting things dry out and water only as necessary will slow the problem. Use yellow sticky traps for the adults and try 1/4" potato wedges inserted in the soil to catch the larvea. Dispose in the trash. Continue your insecticide drenches. Good Luck
