Here's what I do when fungus gnats become too numerous. I spray pyrthrins in my room twice a day. That will reduce them. To elimnate them I add 30ml of pyrthrin concentrate to each gallon of solution and water plants well. I do this every 6 days for 5 applications. That pretty much covers the life cycle of the little buggers. Where I live fungus gnats are a fact of life. They will always come back. I mostly just manage them with the aerosol spray using the other method when they start to get out of control.