Azalea Lace Bug
Egg - The smooth, white egg, which measures approximately 0.4 mm by 0.8 mm, is flask shaped with the neck to one side. It is usually deposited in the tissue of a young leaf along the midrib or a large vein. Each egg is inserted in the tissue with its neck slightly above the leaf surface. Up to 90 eggs have been found in a single leaf. Most of them are placed irregularly along the midrib.
Nymph-Commonly found on the underside of a leaf, the nymph is almost colorless at birth but soon turns black and spiny. It molts six times and ranges in size from 0.4 mm to 1.8 mm before becoming an adult. After the fourth molt, wing pads show distinctly.
Host Plants - The evergreen azalea varieties are preferred by azalea lace bugs, although the deciduous varieties may be attacked. Mountain laurel is also subject to infestation.
Damage - Injury is caused by the nymphs and adults as they extract sap from the undersurfaces of the leaves. The damage shows as spotted discoloration of the upper surfaces of the leaves (Color Plate 1E). In severe infestations, the leaves become almost white, many of them drying completely and dropping off. The undersides of the leaves are also disfigured by the excrement and cast skins of the insects.
Life History - Since its introduction from Japan in the early 1900's, the azalea lace bug has been recognized as an important pest of azaleas. Female lace bugs lay groups of eggs on the undersides of the leaves, most often along the midribs. This egg-laying takes place over an average period of 2 weeks. These eggs require an average of 2 weeks for hatching. Colorless at first, the spiny nymphs hatch from the eggs, gradually darken, and go through five growth stages before becoming adults. Because of the extended oviposition period, it is quite possible to find all stages together on the undersides of the leaves at the same time. Usually two or more generations are produced in a year. The insect overwinters in the egg stage. In the South these overwintered eggs start hatching in late February, building up to a dense population during March, April, and May. A second brood comes along in July, August, and September. During early August eggs are laid. By the middle and last week in September, many adults of this brood are present, the overwintering eggs being deposited at this time and during the first part of October.
Adult females and eggs are protected by the egg sac from virtually any pesticide. The key to control is treatment in late spring and late fall when the nymphs are present. For specific controls, see the current state extension service recommendations.