Fungus Gnats

 Do you ever notice tiny black or orange flying bugs emerging from the soil of your houseplants?

​This could mean you have fungus gnats. Fungus gnats are actually flies that feed on organic matter found in soil, and they can be a real problem when soil is kept moist, because the larvae of these little buggers love to chew on your plants' roots. This can cause stunting and make your houseplants susceptible to other pests and diseases.

Fungus gnat (Katia Schulz) (CC BY 2.0)

Overwatering is a common problem for houseplants and the appearance of fungus gnats means it is time to take action.

First, do not overwater. The use of an inexpensive moisture meter (~$10) is a great way to keep your plants healthy, avoid water waste, and make life difficult for your resident fungus gnats.

Second, since fungus gnats love to eat composting plant material, keep your houseplants free of dead and dying leaves, stems and flowers. Pesticides are generally considered a bad idea in this case.

Finally, you can make your own fungus gnat trap by half-filling a bowl or wide mouthed glass with apple cider vinegar and a few drops of dish soap. Place the container near your houseplants. Adult fungus gnats will be attracted to the smell and drown. This won't eliminate the destructive larvae, but, eventually, you will halt their life cycle. This can also help get rid of fruit flies in the kitchen!

To monitor for fungus gnat larvae in your houseplants, simply put a cut piece of potato into the soil for a few days. A simple magnifying glass should help you see if there are fungus gnat larvae present. Replacing the raw potato every few days can go a long way to interrupting the fungus gnat lifecycle.
​
You can also crumble up a mosquito dunk and sprinkle it over the soil.