Euonymus scale
July 30, 2015
Print
EmailUnaspis euonymi
Hosts
Evergreen species of euonymus, as well as pachysandra, English ivy and boxwood. It is not found on burning bush. Mature females overwinter on stems and leaves. They begin to produce eggs under the scale coverings in early spring. Eggs hatch in late May to early June, and crawlers emerge for about 2 to 3 weeks. There may be 2 to 3 generations per year. Evidence of scale infestation includes yellow spots on leaves, defoliation, and a heavy crust of scales on the stems. Severe infestations can kill the plants.
Female scale (above) is gray to brown, male (below) is slender and white; both are about 2 mm long. The two yellow objects by the female are crawlers.
Management
Target the crawler stage for treatment with horticultural oil. Look for the first generation of crawlers from around the time black locust is in full bloom to when Japanese tree lilac and catalpa are in bloom. The second-generation crawlers emerge in mid-August. The twice-stabbed lady beetle, Chilocorus kuwanae, is an introduced natural enemy of euonymus scale.
Print a PDF of this page: Euonymus scale