Gnats in my house plants #164061 - Ask Extension


Gnats in my house plants #164061

Asked January 13, 2014, 2:31 PM EST

How do I get rid of gnats in my house plants?

New Castle County Delaware

Expert Response

It sounds like you have fungus gnats, which look a little like fruit flies, flying around your house plants.  Fortunately, fungus gnats do not bite humans and do little if any harm to your plants, but they are a nuisance.  The adults you see came from tiny larvae which live in the top 1-2 inches of soil, and the larvae require a moist soil to live in, so the first thing to do is to cut back on watering.  Don't water until the top two inches of soil have dried out.  The larvae feed on algae and fungus, which live in moist soil and feed on decaying plant material, so it is important to clean up dead leaves when they fall into a pot.  Also, planting soil itself breaks down over time, so the presence of fungus gnats may be telling you it is time to repot your plants.  

These stradegies will help you interrupt the life cycle of the fungus gnats, but to get rid of the pesky flying adults, you can put out shallow dishes of soapy water.  Dish detergent works well for this.  (The adults need water but they can't get out of the soap solution.)  That will catch many of the adults.  They also are attracted to yellow, so you might want to try putting out yellow sticky pads (available at a store that sells houseplants).

Good luck and happy indoor gardening!

Gretchen Cox Replied January 14, 2014, 8:56 AM EST

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