Euonymus scales look like small white cottony spots on affected euonymus foliage. Leaves eventually turn yellow and die as feeding continues. Males are white and elongated, and females are brown and oval shaped and about 1/16 inch long. Large numbers congregate on the undersides of leaves, twigs, and stems. About 60 days are required to complete a generation. In Kansas, there are two generations per year. The first generation occurs in the spring and the second in late August to early September.
Overwintering females lay eggs that hatch in mid- to late- May or early June. This period usually occurs when fringetrees, (Chionanthus), cockspur hawthorn (Crataequs crusgalli), Beautybush (Kolkwitzia amabilis) and Late Lilac (Syringa villosa) are in bloom. Crawlers (young scale that have recently hatched) move to leaves and stems and begin to feed by sucking plant juices. Maturing males prefer leaves and females congregate on stems. We have already seen active crawlers in the Wichita area.
The crawler stage is when euonymus scale is most easily controlled. Therefore, check to be sure crawlers are present before treating. Use a magnifying lens to identify the very small crawlers. If nothing is moving, crawlers are not active yet.
Labeled insecticides include malathion and acephate (Hi-Yield Acephate or Ortho Systemic Insect Killer), permethrin (Hi-Yield 38 Plus Turf Termite and Ornamental Insect Control, Hi-Yield Indoor/Outdoor Broad Use Insecticide and Lawn & Garden Insect Killer, Fertilome Indoor\Outdoor Multi-Purpose Insect Spray) or cyhalothrin (Spectracide Triazicide, Bonide Caterpillar Killer).
Control is probably impossible for euonymus that has been heavily attacked and is in very poor health. Therefore, complete removal and destruction of these heavily infested plants (including roots) is suggested. (Ward Upham)