How to Manage Pests

Seasonal development and life cycle—Western grapeleaf skeletonizer

The western grapeleaf skeletonizer has three generations per year in the Central Valley and two generations in the cooler coastal regions. Adults of the first generation in the Central Valley emerge from hibernating pupa in early spring to June. The pale yellow or whitish capsule-shaped eggs are laid in clusters on the underside of grape leaves. After hatching, the larvae line up and feed side by side on the leaf underside until the early fourth instar stages. There are five larval stages. When mature, larvae crawl under the loose bark or into ground litter and spin a dirty, whitish cocoon to pupate.