Q: I have a lot of houseplants, and lately I’ve been having a problem with tiny gnats. I never open the windows, but they’re in the window sill, and they fly around my eyes. What can I do about them?
— Donna Ross, Medina
A: It sounds like your plants have become infested with fungus gnats. The adults like to lay their eggs in moist potting soil, and the larvae that hatch from those eggs feed on fungi and decaying plant matter — and sometimes on the plants themselves.
Insect experts say you can kill the eggs and larvae by allowing the top inch or two of your plants’ soil to dry out between waterings, if the plants can tolerate it. This will also make the soil a less inviting place for adult females to lay more eggs. Be sure not to let water stand in plant saucers.
The adults live only seven to 10 days, so once you’ve started drying the soil, you might want to try waiting for the adults to die on their own. If you can’t wait or the infestation is too large, you can kill them with an aerosol spray containing pyrethrin that is labeled for use on gnats or flying insects. You may need to repeat the application several times if the infestation is heavy. If you prefer an organic approach, you can use insecticidal soap or horticultural oil, but you’ll need to apply it every couple of days.
To prevent future problems, repot your plants periodically.
When growing medium breaks down, it holds more water.
Have a question about home maintenance, decorating or gardening? Akron Beacon Journal home writer Mary Beth Breckenridge will find answers for the queries that are chosen to appear in the paper. To submit a question, call her at 330-996-3756, or send email to firstname.lastname@example.org. Be sure to include your full name, your town and your phone number or email address.