Fungus Gnats are a bad problem if the Amaryllis bulbs are in damp soil. I used to have a terrible time with gnats, I suspect they may have come in the bag of potting soil. I tried lots of home remedies. One year I tried 3% hydrogen peroxide, from the grocery store, diluted 1 part peroxide/ 4 parts water. I let the soil dry out, then watered with the solution. Its supposed to kill the gnat larva in the top 1" of soil. I also put up sticky fly bait strips on all the windows of my Florida room, where my plants are grown, since gnats fly towards the light. It was a losing battle. I've since learned that the best long term solution is to water the pots from the bottom, and keep the top of soil as close to dry as possible. Dry soil is less attractive for the gnats to lay eggs. I don't have a single gnat flying around the potted bulbs this year, so keeping the top of the soil dry seems to have worked for me.
