Hi. I had a Cyprus and tropical plant on the front porch this past summer. I sprayed them with soap and changed the soil when I brought them in this fall. I was then plagued with gnats. I have done sticky tape, a sticky tape light, soap and even tried Hydrogen peroxide 3%. 4 tbsp per quart water to treat for eggs. They finally killed another tropical that was beside them. I finally put the two plants both outside again to get ahead. It seems to be working but it is getting cold out. Any suggestions?