Ceanothus leafminer

Ceanothus leaves show blotchy, irregular mines or tunnels as tiny larvae feed inside leaf tissue starting in late spring through summer. Look for discolored patches that may eventually cause affected leaves to brown and drop. The damage appears throughout the growing season on wild lilac species. Infested foliage becomes unsightly but the plant usually recovers, as ceanothus is vigorous.

This is primarily a cosmetic issue that rarely threatens plant survival. Prune out heavily mined branches and discard them to reduce leafminer population. Allow natural parasitoids to establish; they control populations effectively without intervention. No chemical treatment is typically needed for landscape plants, as damage tolerance is high and populations self-regulate through natural enemies.