You need to do more than the drier sheets for control of the fungus gnats. I wouldn't recommend just living with them. They have the potential to spread diseases.. some of which have no cure and result in contagious spread ultimately causing you to destroy your plants. I say this because I am currently living out that scenerio. I can't blame it on the fungus gnats, I'm just saying that they have potential to help spread diseases to kill plants, if they don't kill plants themselves first.