Western grapeleaf skeletonizer

Harrisina brillians

The metallic bluish or greenish black western grapeleaf skeletonizer moths fly during the day. Body length is about 0.6 inch and the wingspan is 1 to 1.3 inches. There are three generations per year in the Central Valley and two generations in the cooler coastal regions. Adult moths 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. The first two stages are cream colored, the third stage is brownish, and the fourth and fifth stages are yellow with two purple and several blackish bands. Larvae have conspicuous tufts of long black poisonous spines that cause skin welts on field workers. The fifth or last larval stage is about 0.6 inch long. When mature, larvae crawl under the loose bark or into ground litter and spin a dirty, whitish cocoon to pupate.

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