Western grapeleaf skeletonizer—Harrisina brillians
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
Skeletonizers first eat the undersurface of leaves. Later all leaf tissue between the main veins is eaten,
causing a "skeleton" effect.
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.