Damage Whiteflies suck plant juices from leaves. Severe feeding may reduce photosynthesis. During feeding these insects exude a sticky substance, called honeydew, that makes plants unsightly when in excess, and also serves as a development site for a black, sooty mold. Feeding by large numbers of whiteflies may stunt whole plants or plant parts. Control Chemical Control.
Whiteflies are hard to control.
However, with the proper materials and conscientious application, control can be achieved. A serious problem in adequate chemical control, particularly in the greenhouse, is that whiteflies develop resistance to specific insecticides. Resistance may be delayed by alternating types of chemicals. Unfortunately, there is no way to known when this should be done. Individuals must be on guard and act when any appearance of resistance arises.