Azalea Whitefly: Appearance, Territory, Damage, and Life Cycle

Latin Name: Pealius Azaleae

Appearance: Whiteflies are sap-sucking insects of the order Hemiptera, suborder Sternorrhyncha’s family Aleyrodidae. They are 1-2mm long and have a white waxy substance on their wings. Adults resemble small moths when at rest. The immature nymphs are mostly pale yellow and seem scale-like. The little nymphs are oval in shape and pale in color, with no wax secretions. The pupal case is light yellow to orange-yellow in color, free of wax secretions, and is 0.84 mm in length. The hue of the peripheral portions is lighter than that of the mid-dorsal area. When the pupal case has developed against the leaf hairs, some marginal indentations may be evident.

Hosts Plants: Azalea whiteflies infest all azalea cultivars. Infested plants become wasteful, and honeydew and sooty molds detract even more from a healthy appearance. When strongly afflicted plants are disturbed, clouds of adults may form.

Territory: This whitefly has spread over the world wherever azaleas grow. In the United States, the first records were made on plants brought from Holland in 1910. Azalea whiteflies are unmistakable in all southeastern states.

Damage Insect Cause: A swarm of tiny white flying insects coming from a plant when its leaves are disturbed could be the first symptom of a developing whitefly infestation. Whiteflies (Trialeurodes vaporariorum) can quickly conquer a plant, entering the stems and draining away the life-giving liquids within if left untreated. Infested plants become wasteful, and honeydew and sooty mold detract from their beauty. When strongly afflicted plants are disturbed, enormous clouds of whiteflies take to the air unless they are controlled.

Life History and Habits: Females lay their eggs on the underside of azalea leaves. The eggs hatch into tiny yellowish crawlers that look like motile pollen grains. Crawlers eventually put their threadlike mouthparts into the leaf and begin sucking sap. Crawlers molt into pale, scale-like insects known as nymphs, which also consume sap. Mature nymphs’ range in color from light yellow to orange. Crawlers, nymphs, and adults all emit honeydew, a transparent sweet liquid. Sooty molds are fungi that develop in honeydew and cause azaleas to turn dark – sometimes almost black! Sooty molds can harm the shrub by blocking sunlight from the leaves and shading it out.