Indoor Plant Gnat Problem

Asked January 6, 2018, 8:07 PM EST

Hello. I am having an issue with my indoor plants. They have gnats bedding in the dirt. I have tried a couple of home-remedies (including using apple cider vinegar and also fruit traps) but to no avail. There are gnats everywhere. I don't overwater, but I do have tropical plants. I have put rocks on the top of most of my plants to try and reduce the dirt exposure. It helped a little but I still have the problem. Is there a product or solution you would recommend.

Lapeer County Michigan

1 Response

Hello,

Fungus gnats, sometimes called root gnats, are fairly common insects that are generally found in moist, shady places. The larvae of most species live in moist or wet habitats and feed on fungi. Some have been reported as being occasional pests in mushroom cellars. Those found in Michigan homes commonly come from soil in potted plants. Another source is decaying vegetable matter, like an old bag of potatoes or some other forgotten, wet organic material. The best method of controlling the larvae in these situations is to remove and discard the infested material or to prevent a wet area from staying wet. Any household aerosol containing pyrethrins (e.g. Raid) should control the adults. Allowing potting soil to dry out a bit between waterings will usually reduce, possibly eliminate fungus gnat problems coming from houseplants. If this doesn't take care of the problem then replacing the soil with new, sterilized soil is another effective means of control. A more slightly more aggressive approach is to use a microbial insecticide drench such as Gnatrol (see http://www.planetnatural.com/site/gnatrol.html ) to kill larvae in the soil.

W.S. Cransaw and R. A. Cloyd at Colorado State University have written a very nice article on fungus gnats, read it at: http://extension.colostate.edu/topic-areas/insects/fungus-gnats-as-houseplant-and-indoor-pests-5-584/

Be sure to read and follow all the instructions and safety precautions found on the pesticide label before using any pesticide.