I was given a houseplant that had a gnat problem that spread to the rest of my house. I have seasonal gel window clings on my patio windows and noticed literally hundreds of fungus gnats permanently stuck to the gel clings, so I removed the gel clings from my windows. Next I placed them in bowls and also stuck a few in my houseplants with toothpicks. My fungus gnat problem is 100% gone! Try it and see. I went to a local arts and crafts store and the gel (not the flat kind) window clings were $3 at most. Happy houseplants!
Thanks Entwined! I had the gnat problem for months before I discovered they liked sticky gel window clings so well! I found this forum online so that I could help other people with the same problem.