Rhododendron lace bug

On rhododendron leaves in the Puget Sound region, look for pale stippling on upper surfaces with dark, varnish-like tar spots covering the undersides; this is the hallmark of Stephanitis rhododendri feeding. Nymphs are spiny, dark, and develop through four growth stages while clustering among their own dark fecal spots. By mid-July, heavily infested leaves appear severely yellowed or whitened.

Scout undersides of leaves in early July for the first visible damage. Reduce nitrogen fertilizer to decrease plant attractiveness. Horticultural oil with thorough undersurface coverage suppresses all life stages if applied early. Bifenthrin or malathion provide stronger control, though oils are preferred.