My greenhouse is infested with white flys help. I have lots of tomatoes and herbs, and I keep trying different sprays, and just cannot get rid of them.
they are really hard to get rid of. Lots of greenhouses use that yellow sticky paper. You hang it up near the plants and the white flies are attracted to it. You can buy it on line. Our small garden stores don't have it; kind of a specialty thing.
Fly tape is a cheap alternative to yellow traps and work very well. Need oil will knock them down. I quit growing winter indoor tomatoes because I could not keep them under control. The big thing is prevention. I would get an infestation from store bought flowering plants. Poinsettias carry a lot of pests. I started using an insecticide that is systemic for flowering plants. Not on anything edible.