Pest description and damage The cotoneaster webworm is a dark brown caterpillar, 0.25 to 0.5 inch long. It typically webs clumps of leaves together and feeds within tubes snaking along the branches. Beside unsightly webbing, larvae skeletonizing leaves. Death of branches can occur. The webworm is primarily a problem on Cotoneaster horizontalis (rock cotoneaster) and only in some years.
Biology and life history The caterpillars feed during the summer and fall, overwintering in nests on the plant. They pupate in the spring giving rise to dark gray, night-flying adult moths. Eggs are laid in spring.
Scouting and thresholds Search for webbing that follows along the main branches among the leaves.
Hand-pick and destroy larvae; prune out nests.
The fact that populations rise and fall indicate that natural enemies are present in most years.
Management-chemical control: HOME USE and COMMERCIAL USE
See "Caterpillar" in:
For more information
Johnson, W.T. and H.H Lyon. (1991), Insects That Feed on Trees and Shrubs. 2nd ed., (p. 218).