Tentiform leafminer

Tentiform leafminers create distinctive, grayish, tent-like folds in apple leaves and other hosts, with larvae feeding inside the mine. Initial mining appears as a small bump on the leaf surface. Folded leaves become visible by midsummer in western Washington. Heavy infestations can cause leaf yellowing and premature drop, primarily affecting landscape crabapples and Serviceberry.

This is predominantly a cosmetic concern for ornamental trees. Prune off infested leaves in early summer to reduce pest numbers and improve appearance. Do not spray, as leafminer parasitoids (including Eulophid and Pteromalid wasps) are disrupted by pesticides and naturally suppress infestations. Maintain tree vigor to support rapid foliage replacement.