Oak Treehoppers

You will observe small triangular or spiky insects clinging to oak twigs and the undersides of leaves. Treehoppers are tan or brown, one-quarter inch long, and often camouflaged against bark. Nymphs cluster on twigs, sometimes covered in protective waxy coating. Adult females lay eggs in slits made in bark, creating visible damage lines. Puget Sound oaks host these generalist feeders from spring through fall.

Treehoppers cause minimal damage and are part of the natural oak ecosystem. No chemical control is justified. Remove egg-laden twigs during pruning if bark damage is objectionable. Maintain tree vigor and accept light feeding damage. Predatory insects and birds help control populations naturally.