Origin:
Possibly native to North America.
Biology:
Primarily a pest on iris and gardenias, but they also infest many vegetables, landscape plants, and cotton. There usually will be a great amount of wax associated with infestations of this species, creating a powdery white appearance to the lower surface of the leaf. Females deposit up to 400 eggs in their lifetime, averaging about 25 eggs per day, in small groups that often are arranged in a circular pattern and usually on the lower surface of the leaf. Each egg is attached to the end of a short stalk. Nymphs are mobile in the first instar, but lose their legs become sessile and feed in one place in the next nymph stages, covering themselves with a waxy layer. The nymph stages take about 1 month to reach the immobile pupa stage. All stages feed on the plants. Heavy infestations may nearly cover the entire surface of the leaf, with heavy production of honeydew and sooty mold.
Identification:
The adult is powdery white with a black dot on each wing, and resembles a tiny white moth. The wings of the adult are more rounded at the tips than some other species, and the wings are held almost flat over the abdomen when at rest. The pupa stage has only a row of short hairs circling the body, and not the long filaments of the greenhouse whitefly and others. The female tends to coat an area of the leaf surface with powdery wax, closely resembling powdery mildew, and deposits the eggs one at a time within this area.
Characteristicts Important to Control:
Initiating control as soon as a few whiteflies are noticed will increase the chances of success. Contact insecticides often provide very little control due to the repellency of the wax on the insect and the occurrence of resistance to may insecticides. A systemic product that can penetrate the plant’s tissues may be most effective. Horticultural oils also will help by coating the insects and smothering them. Reapplications at 5 to 7 day intervals may be needed, and any sprays should be directed at the lower surface of the leaf and applied thoroughly. Bright yellow sticky traps can be very successful at capturing large numbers of the adult insects.
