Fungus gnats travel indoors

Q. How do I get rid of gnats? I don’t have any fruit left out. They are smaller than fruit flies. Please help!

Barbara from North Jackson

A. Without a sample, it is usually challenging. But this is one case that I can say it is most likely fungus gnats that are causing “dancing hands” and general annoyances around Barbara’s house!

Fungus gnats are common household problems in winter months. Most often, they are brought inside the home on house plants that were enjoying the summer weather outside. They are rather small, being only a quarter inch in length. Although they are not fast flyers, they seem to easily escape the dancing hands of homeowners and guests alike. Just when you think you’ve controlled them or they’ve finally died out, they return with a vengeance to annoy once again.

Fungus gnats only live four weeks, but each female can lay up to 100 eggs! So just a few can lead to increasing numbers if they aren’t controlled.

They feed on decaying organic matter in the soil as well as fungi. The key to their feeding is moisture. Without moisture, survival of eggs and maggots is reduced to near zero. The problem is – houseplants need moisture and humidity.

The solution is growing houseplants as dry as possible. Use your finger to test the soil moisture and only water plants when the soil is dry. Do not let them wilt, but let them get close.

Remove every possible area for water to hide or accumulate around houseplants. This includes checking trays under plants for excess water, reducing any mulch layers around plants and removing any dead/dying leaves from the soil – just throw these in the trash. Improving drainage of the containers used for houseplants will help soil dry more quickly between waterings.

Yellow sticky cards are a great tool to catch these invaders. Place cards just above the soil surface for best results. These traps are usually 3”x5” cards that are yellow in color and sticky to the touch. They are available for less than $1 each on many ecommerce sites and home and garden stores.

Chemical controls are not generally recommended due to the plants being inside the house, and they will only kill the adults. Larvae will simply pupate and emerge as adults to keep the cycle going. Dry growing and a general cleanup of containers and trays should do the trick in just a couple of weeks.

To see photos and learn more about these insects, go to:

Eric Barrett is OSU Extension educator for agriculture and natural resources in Mahoning County. Winter hours for the Plant and Pest Diagnostic Clinic vary. Submit questions to the clinic at 330-533-5538 or drop samples off to the extension office in Canfield.

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