I started a lot of seeds this year, mainly Tomatoes and Peppers. I seem to have also planted an unwanted guest. Fungus Gnats!
Fungus gnats thrive in damp, moist environments. You know, kind of like what you need to start seedlings. They are also a common houseplant pest. The larvae can cause serious damage and even death to young houseplants and new seedlings. However, Fungus gnats are typically harmless to healthy mature plants, they are just no fun to have living inside your home.
The adults are small (1/8 inch long), mosquito-like insects, with long legs and antennae.
They look like this:
Shown MUCH larger than actual size!
The fungus gnat's life cycle from egg to adult may be completed in as little as three to four weeks depending on temperature. Eggs are laid in cracks and crevices in the media surface and mature in four to six days. Fungus gnat larvae feed and develop for about two weeks at 72 degrees. Basically, the temperature you probably keep your home. After four to five days, adults emerge. Overlapping and continuous generations make control difficult.
Recent studies have shown that fungus gnats may be introduced in soiless media.
One of the best ways to control them is to make sure your soil completely dries out between waterings, and get rid of decaying stems and leaves. Don't let your plants become too stressed for water though. Other ways to control them include, watering with a solution of Bacillus thuringiensis, an organic control for caterpillars, to kill insect larvae. If the infestation gets too bad, you can drench the soil with a solution of pyrethrin, an organic pesticide made from chrysanthemums. Make sure you read and follow the directions. Always try the least toxic method of pest control as your first step.
I will be putting the plants outside soon. I have started to allow the soil to dry out a little more between waterings. Hopefully soon, I will be able to say no more naughty gnats!