Natural, Nontoxic, Vegan Fungus Gnat Control
It's happened to many of us: we bring in houseplants for the winter, or let a banana stay out too long, and before you know it, your house is filled with those annoying little pests, flying in your face (and I should know, I inhaled one!) and making your life miserable. Never fear, I conquered my gnat infestation (mine came about because I didn't wash organic lettuce before bringing it inside), and you can, too!
I have tried several methods, and all of them work. It's just a matter of choosing the right method for you. This will depend on your personal preferences, as well as your home environment.
First off, try to determine the original source of the infestation. In the case of bananas left out too long, or the unwashed organic lettuce, you don't have to do anything else except prevention. But if your source is houseplants, or leaks in your roof, windows, or walls, you will want to fix this problem first, or the infestation will happen over and over again.
Fungus gnats feed on decaying organic matter, and so decaying wood is a perfect food source. If it turns out that this is the case, call a certified professional to deal with your problem, whether that is a roof or a window, or something else (this may even be a sign of a more serious problem, such as termites).
In the case of houseplants, letting the top two inches of soil dry out completely will prevent more infestations from occurring. A layer of mulch or sand may deter future infestations.
These pests are attracted to the color yellow, and to the odor of fermenting stuff, so these two factors will be the basis for our control.
How have you tried to deal with a gnat infestation?
Sticky flypaper will work just fine to catch the adults, which are the most annoying. It's important to catch the adults as much as possible because the female will lay up to 300 eggs in its lifetime, and therefore you don't want the infestation to get any worse.
Another method for catching adults is to use vinegar (or any fermented product). I had the best success with a few drops of wine or beer in two ounces of water, and a single drop of dish soap in a yellow container (I used a plastic lid from a margarine container). The gnats will fly into this, become intoxicated, and drown. You can use white vinegar and add a little sugar, or apple cider vinegar. The dish soap is essential to alter the surface tension of the water. Be sure to change this every few days or the smell will be overpowering.
You can also use the soda-bottle trick. Cut a soda bottle in half, and remove the label. Remove the lid and drill a small hole in it, then replace it. Put something that will rot (a banana skin, a piece of fruit, etc.) in the bottom half and cover with water, then invert the top half and insert it into the bottom half. The gnats will fly through the hole but won't be able to get back out (see the video if you're having problems understanding this).
Larvae Trap for Houseplants
There is an easy way to get the larvae to come to the surface of the soil so that they can be disposed of. Simply cut small slices of raw potato and lay them directly on the soil. After twenty-four hours, turn the potato slices upside down, and if you have fungus gnat larvae, you will find them feeding on the potato. Simply take potato and all and dispose of it however you think is best.
Make Your Own Sticky Paper
This is very easy to do. Simply get yellow construction paper, yellow posterboard, post-it notes, or anything yellow. Paint with one (not all) of the following:
- Rubber cement
- Petroleum jelly
- Corn syrup
Place this anywhere you have seen the gnats. It can be hung up or laid down. The fungus gnats will stick to this and you can just throw it away.
A Not-Quite Vegan Solution
Although this does not involve killing anything but fungus gnats, some ultra-strict vegans may be uncomfortable with this method. It involves introducing nematodes (microscopic worms) into your houseplant soil. These worms will eat the fungus gnat larvae and save you a great deal of trouble. Nematodes also control a number of other pests, including fleas and slugs, so if you feel okay about using this method, it will probably be worth it.