Lace bugs use their sucking mouthparts to feed on plant sap. Damage ranges from scattered small white spots to complete bleaching of leaves. Some species feed on many different types of plants while others feed only on a narrow range or single species. Injury builds slowly but can become very intense late in summer. Adult and nymphal stages of the same species can look very different, which can confuse identification.
Azalea lace bugs, about 1/8 inch long with light brown bodies, are one of the common offenders. They prefer evergreen varieties but also attack deciduous varieties and mountain laurel. Sap removal by adults and nymphs, which feed on the underside of leaves, causes a spotting visible on the upper surface. In heavy infestations, leaves may turn white and drop prematurely. Spots of their tarry excrement build up on the undersides of leaves. The lacy wings of the adults have dark brown to black markings; nymphs are black and spiny. Populations are greatest in mid- to late summer as the second generation bugs appear.
Insecticidal soap (Safer) can be used to reduce lace bug numbers. The spray must be directed to the undersides of the leaves to contact the insects directly. The treatment may need to be repeated to bring populations under control.
By Lee Townsend, Extension Entomologist