University of Maryland Extension

Euonymus Caterpillar - Shrubs

close up of webbing from caterpillar
Webbing caused by euonymus caterpillar 

Return to Common Problems of Trees and Shrubs

The euonymus caterpillar is an introduced pest of Euonymus. Species attacked include European Euonymus (Euonymus europaea) (the tree form); Spreading Euonymus (E. kiautschovicus); Winged Euonymus (E. alatus) and Japanese Euonymus (E. japonicus). The larvae (caterpillars) appear in central Maryland in early to mid-Mary. The young larvae are gregarious (feed in groups). They web the foliage together and feed on new growth. Webs increase in size as the larvae grow, eventually enveloping large branches. Feeding lasts for about 3 weeks before pupating in June. Mature caterpillars are about 20mm long. They are creamy-gray color, with black spots and black heads. Moths are small (wingspan: 24mm) and white with black spots. They emerge in mid-June and lay eggs on twigs, branches, and axils of buds. The eggs hatch by early August, but instead of feeding, the larvae immediately prepare for overwintering. No further activity is seen until the following spring.

euonymus caterpillar on webbing
Photo:  Euonymus caterpillars on webbing

Management: Since there is only one generation and the feeding occurs early in the season, control is seldom warranted. Euonymus outgrows the damage by the end of summer. Bt (Bacillus thuringiensis) may be used on young caterpillars if damage is unacceptable.


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