Eco-friendly Control for Fungus Gnats
Don’t worry if you notice small fruit fly-like insects flitting across the room. It is not a sign of bad housekeeping nor are they harmful to your plants.
These small insects, known as fungus gnats, are feeding on the organic matter in the soil. They are not harmful, but can be annoying. If possible just live with them. As they go through their lifecycle the populations will rise and fall.
Allow the potting mix to dry slightly between watering. Since the fungus gnats thrive in moist organic soil, the drier conditions will help reduce their population.
If you are still bothered, you can use an organic insecticide, like Mosquito Bits® with the active ingredient Bacillus thuringiensis israelensis, known as Bti. This bacteria kills the larvae of fungus gnats and mosquitoes, but is safe for people and pets. You may need to order on-line or through a garden catalogue. And as always be sure to read and follow label directions.
A bit more information: Some gardeners report success trapping these insects. Fill a drinking glass or container halfway with cider vinegar. Then cover the opening with clear plastic wrap and secure. Punch a small hole in the plastic wrap. The idea is the fungus gnats, attracted to the cider vinegar, fly in through the hole, but can’t find their way out.