There are five distinct stages, which have different tolerances to insecticides. Eggs are resistant to all but a few insecticides. The crawlers are quite susceptible to contact insecticides. The adults fly from plant to plant seeking new sites to lay eggs. Adults are most easily controlled with a fumigant or space spray, although contact insecticides are also effective.
All life stages can exist simultaneously as generations overlap.
Thus, a single application of a particular insecticide only affects susceptible stages, leaving the other stages to survive and reproduce. Once adult whiteflies are noticed, all stages probably exist in such large numbers that frequent and regular applications of an insecticide are necessary. Be sure to inspect all new plants brought in for whiteflies. If present, pick off all stages on infested plants, treat with an insecticide, or discard by burying. These yellow boards should be about 1 foot square.