The last generation of Azalea lace bug is now active in Delaware. The following is more information.
Last Generation of Azalea Lace Bug Active
Azalea lace bug (Stephanitis pyriodes), nymphs and some adults are present in Delaware. The adults will be laying eggs in October and the insects overwinter in the egg stage. The eggs are inserted into foliage, usually along the midvein area. We usually see nymphs in May in Delaware and can see at least 2 to 3 generations per year. In southern Delaware where the growing season is a little longer the 3rd generation is more likely. Azalea lace bug populations tend to be highest when plants are grown in full sun and the damage can be the most severe at these sites.
Cultural control: The best thing you can advise your clientele to do is to stop growing rhododendrons and azaleas in full sun and move them into areas of filtered shade or landscapes with shade part of the day. Also, keep pH low with acidic mulch (pine needles, pine bark) and soil moisture even. A stressed plant is more likely to show heavier injury.
Chemical Control: Imidacloprid has been used by most landscape managers for the last decade. Some are starting to use some of the newer neonicotinoids such as Flagship and Safari for lace bug control. The imidacloprid has controlled both species of lace bug for at least a full growing season. We have had several landscape mangers report that they continue to see control carry into a second season.
Photo of azalea lace bug damage by Whitney Cranshaw, Colorado State University, Bugwood.org
Adapted for Delaware from an article in the September 25, 2009 edition of the TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers from the University of Maryland Cooperative Extension http://www.ipmnet.umd.edu/09Sep25L.pdf