Q: When should I treat my azaleas for lacebugs? 

A: The easiest way I’ve found to control azalea lacebug is to apply a systemic insecticide drench that contains imidacloprid (click for sources) in spring, after the azaleas bloom. This will protect any beneficial insects that visit the flowers. The drench poisons the leaves, so lacebugs that suck sap from them are dead within days.