Plantscaping Expert, Dale Crable answers tough questions about your favorite houseplants.
WHO NEEDS FUNGUS GNATS?
Santa Cruz Sentinel Article
A fungus gnat is a pesky bug that resembles a small mosquito. They have black bodies and gray wings. A rather poor flier, they remain near the interior plant foliage and soil; taking to the air when disturbed.
To control fungus gnats and keep us from clapping our hands together trying to smoosh them; it is important to understand their life cycle. The eggs are laid in the soil, preferably a moist peaty one. They can hatch within 4 days. The larvae are clear and feed on decomposing organic material and roots. The total life cycle takes 2-4 weeks. The adult gnat only lives around 7-10 days.
Now, what to do about this annoying pest... Controlling adults is as simple as using the yellow sticky cards for white flies. The larvae however, is where our attention should be directed. I offer three solutions.
1. Remove top 2 inches of soil and replace with sterilized soil.
2. Use a soil drench by adding some dishsoap to your watering can each time you water for a couple weeks.
3. Lysol aerosol sprayed on the soil seems to help greatly. Do not be afraid to water it in.
My favorite is to leave a glass of wine near infected plants overnight and count the bodies in the morning.