I have been growing some herbs on my windowsill. Lately I've noticed an infestation of white flies that seem particularily attracted to my sage, oregano and thyme, but not my chives and rosemary. I need to get this under control fast before they get to my orchids. For obvious reasons, I'm looking for a natural way to eliminate them once and for all. I've tried a mild soap solution (not quite natural, I know) but they came right back. Thoughts? Solutions? Thanks.