Did you observe small bunches of dead leaves in your cotoneaster shrubs last spring? This webbing, usually most evident in late May or early June, is caused by the cotoneaster webworm. If this condition was noticed last spring, observe your cotoneaster shrubs for the next several weeks.

The cotoneaster webworm over winters in the masses of dead leaves on the shrubs. In the spring they develop into adults, which eat for a short period of time on cotoneasters and then lay their eggs. In late July and early August, the eggs hatch and the larvae will begin devouring the leaves. The larvae is dark brown in color and up to an inch in length. At the first sign of feeding, apply a chemical treatment. Use Diazinon, Malathion or Sevin. Other insecticides labeled for leaf feeding caterpillars such as Tempo can also be used. The active ingredient in Tempo is available in Bayer Advanced Garden Multi-Insect Killer.  When using insecticide, mix and apply according to label directions. If webbing has already been produced, it must be thoroughly wetted in order to achieve control of the webworm.

This page was last updated April 2003

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