Fungus Gnats

Summary: Do you l ove to over-water your favorite plants? Keep it up and you will find yourself fighting fungus gnats. The mosquito-like funus gnat will occasionally become a nuisance from over-watered potted plants or flower boxes.

A reader asks: We have been bitten by gnats for weeks now. We have a lot of plants in a small office area. The "plant lady" put little yellow stickies in them to see if the plants might be the source. When she returned to check them she found fungus gnats and sprayed the plants. However, some employees found the gnats dead in their windows so they stopped her from spraying assuming that the gnats were coming from the mulch outside. I don't agree. Please advise.

Dear Reader: Fungus gnats occasionally become a nuisance indoors when adults emerge in large numbers from potted plants or flower boxes containing damp humus-rich soil. The adult fungus gnats are attracted to lights and are often first noticed at windows.

Fungus gnat larvae feed in soil that is high in organic matter. This gnats are capable of injuring the roots of various foliage plants. Affected plants will show symptoms of sudden wilting, poor growth, yellowing and foliage loss.

Over watering planters, water leaks and poor drainage can result in a buildup of fungus gnats. Allow soil to dry as much as possible without injuring the plants. This process will kill many of the fungus gnat maggots.

Remember that houseplants taken outside during warm weather may become infested with insects, so check them carefully before bringing them back indoors.

Although adult fungus gnats are killed easily with pyrethrin sprays or aerosols labeled for "gnats" or "flying insects, I would suggest having the plant maintenance company do the treatments. They should be licensed for handling pesticides. You should not be applying pesticides in a public location without a license.

Now, the bad news. Fungus gnats do not bite people. They don't have the mouthparts that would enable them to bite.  So, I haven't solved your problem yet. Keep investigating! It's got to be something in addition to the fungus gnats, so you'll need to keep putting out glue traps to try to trap the culprits.