Heather Olivia wrote:You're certainly not the only one to struggle with such critters in your composting toilet. We have struggled with what I believe are fruit flies in ours, despite many efforts to exclude and eliminate them. You're right, it's definitely unsettling.
From reading about fungus gnats, it sounds like when growing plants, they can be an indicator of overwatering and that allowing the soil to dry can serve to reduce their numbers greatly. Adding a layer of sand, mulch or diatomaceous earth was also suggested.
I know something we have found helpful, although not a total solution, is more frequent emptying of our toilet chamber (bucket, in our case). Every few days, or maybe even daily, so as to interrupt their reproductive cycle and reduce the numbers.
I have a suspicion (confirmed in the article below) that the peat moss may be a carrier for fungus gnats. Whether it's the source or not, it probably does encourage them. Especially since it is damp. Could you perhaps use a different cover material and see if that helps? This article has some suggestions for natural ways to eliminate fungus gnats. Hope you find a solution! https://yourindoorherbs.com/get-rid-of-fungus-gnats-soil-home/