Looper

Western oak looper (also called looper caterpillar) larvae are smooth, slender inchworms that feed on oak foliage. Damage occurs as leaf notching along edges and skeletonization between veins. Multiple larvae can cause significant defoliation of host trees. Though more common east of the Cascade crest, occasional populations may reach western Washington oak plantings in dry years.

For landscape oaks experiencing moderate to heavy defoliation, monitor tree recovery the following season. Most oaks tolerate one year of defoliation without long-term damage. Prune heavily defoliated branches to redirect energy. Natural parasitoids suppress looper populations. Avoid broad-spectrum pesticides.