University of Maryland Extension

Euonymus Caterpillar - Shrubs

caterpillar of euonymus 
Euonymus caterpillar

Key Point

  • 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 
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.


Rev. 2020

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