Euonymus scale

July 30, 2015

Unaspis euonymi


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.

Euonymus scale

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.

Euonymus scale mature male


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.

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