How to Manage Pests

Pests in Gardens and Landscapes

Western grapeleaf skeletonizer—Harrisina brillians

Identification

Young skeletonizer larvae are cream colored. Older larvae are yellow with two purple and several blackish bands. Each body segment has four tufts of long, black stinging spines. Mature caterpillars are 0.5 inch long. Adults are metallic bluish to greenish black moths. Their wing span is 1 to 1.3 inches.

Life cycle

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.

Damage

Skeletonizers first eat the undersurface of leaves. Later all leaf tissue between the main veins is eaten, causing a "skeleton" effect.

Solutions

Larvae are attacked by naturally occurring parasites as well as by a granulosis virus disease. Applications of spinosad or Bacillus thuringiensis are effective for controlling skeletonizers. Good spray coverage on undersides of leaves is essential.

Adult moths
Adult moths

Mature larvae
Mature larvae

Skeletonized leaves
Skeletonized leaves

Spots by larvae
Spots by larvae


Statewide IPM Program, Agriculture and Natural Resources, University of California
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