The Q&A Archives: Fungus gnats in house plants

Question: i have what I believe to be fungus gnats in my plants (they look like flying ants). I have repotted the plant that I believe is the culprit, sprayed it with a fungus gnat spray, and put ant powder on the soil of all the plants in question. I have also fed them a mixture of house vinegar and water. The good thing is that they are basically dead when they come out.

But what is the best way to get rid of them, other than actually getting rid of the plants? I understand that ensuring they are thoroughly dry between waterings is a good thing to do to kill them off...


Answer: Here are two strategies for controlling fungus gnats. They breed in moist potting soil, so you can break the breeding cycle by allowing the surface of the soil to dry out. If you have plants that need moist soil simply place a quick draining and fast drying layer of gravel or sand on top of the potting soil. This will act as a barrier to the soil. Or, you can drape plastic wrap over the soil (cut a slit so you can place it close to the stems of your plant, then overlap the cut ends so the pests cannot find a way to the potting soil). You have to be a little patient with this method because you have to wait through the next generation's maturation before they are gone for good. In other words, once the generation now already in the soil become adults and die off without being able to reproduce, there should be no more gnats. Another method is to use a product called Gnatrol as a soil drench, another is to use an insecticidal soap as a soil drench. Of course, always follow the label instructions carefully. I hope this helps!

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