Azaleas are in bloom right now, but you may also have noticed leaves that look like these:
The azaleas in this photo from James L. Castner, University of Florida, have healthy new growth as well as previous damage from lace bugs. Lace bugs (Stephanitis pyrioides) are a common pest of azaleas here in NC. Nymphs and adults feed on the chlorophyll-containing tissues of azalea leaves, which gives the leaves a pale, spotted appearance. While this is mainly a cosmetic problem, if the infestation is great enough it can lead to early leaf drop and increased susceptibility to dieback diseases.
The adults and nymphs are tiny and can be found on the undersides of leaves, along with their waste and eggs. Nymphs have black markings and are spiny, while adults are cream colored with lacy wings. Lace bugs overwinter as eggs and may have 2-4 cycles per year.
(Photos: James L. Castner, University of Florida)
The first generation of lace bugs are usually active in April and May here in NC. Planting resistant cultivars of azalea and providing proper growing conditions will reduce damage. There are several beneficial insects that feed on lace bugs, including lacewings, assassin bugs, and spiders. If you have an infestation that is causing unacceptable aesthetic damage, Clemson University suggests the following control measures:
Insecticidal soaps may give some control of young lace bugs, and complete coverage of all leaf surfaces is essential. For adult lace bugs, recommended spray insecticides include bifenthrin, lambda cyhalothrin, malathion, carbaryl, and cyfluthrin. These insecticides are contact insecticides, and sprays need to be directed onto the lower surface of the foliage to be effective. Azaleas should be sprayed when the first lace bugs appear. A second application in seven to ten days may be needed to control newly hatched lace bugs. Good control of the first generation in March to May will greatly reduce problems later in the season. Control of second (July to August) and later generations (September to October) may be necessary.
Systemic insecticides are no longer recommended due to the danger of harm to bees.
As with all pesticides, read and follow label instructions. Additional information, including pesticide information, can be found here. Please keep in mind that insecticides also harm beneficial insects, so they should be used with caution and only when necessary.
More information: http://entomology.ifas.ufl.edu/creatures/orn/shrubs/azalea_lace_bug.htm