Answer: Whitefiles are generally more of a problem indoors on houseplants, or inside a greenhouse, than they are on outdoor plants. (There's a parasitic wasp that attacks them outdoors.) The pests can be quite prolific where the temperatures are constantly spring-like, and the humidity around plants is high, like it is indoors or in a greenhouse. Whiteflies can be discouraged by hosing off the infected plants, making sure to direct the spray on the stems, branches, under and upper sides of the leaves to dislodge the eggs, as well as the adults. You can make sticky traps out of bright yellow cardboard or paper, smeared with petroleum jelly, and placed at the leaf-level of your plants. The whiteflies will be attracted to the yellow color and will get stuck on the sticky surface. Replace the traps when they are no longer effective.
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