We answer all sorts of vermiculture questions from our customers and I participate on vermi forums to try to help solve problems. Lately, there have been a lot of questions regarding how to get rid of fungus gnats.

Fungus gnats like to live and breed in moist environments. The big key is to maintain your bin so that you are not setting up a hospitable environment for them. Basically, you want to suppress or cut them off from the area that they like. How do you do this?

A few years ago, we had a problem with fungus gnats in our house plants. I covered the top of the dirt with sand. The sand still allowed for water to go through and some air, but the gnats couldn’t. This solved our problem. While this worked for our house plants, I don’t recommend this for your worm bin. There is an easier way to deal with this situation.

Our bins are open at the top. We cover them with burlap and an inch layer of dry shredded newspaper. Instead of burlap, you could use an old cotton t-shirt. This makes it very difficult for the fungus gnats to get to the moist castings and bedding. We also believe that the fungus gnats will “set up house” in moist cardboard. Leaving this on top of the bedding or exposed provides an ideal environment for the gnats.

Here is a comment from Erick, a fellow vermicomposter after he followed our advice:
“As it turns out it was an excellent tip. Just the t-shirt has stopped the current population from expanding and the few stragglers should be gone soon. Awesome results and in so very few days. Thanks again! Ha ha, having a swarm fly out of the bin made it pretty hard to promote the cause to people that have shown some cautious interest, but this definitely helped.”