Question
My Euonymus tree seems to have an infestation of bugs or perhaps scale. Many little white things on the underside of leave and on the branches slowly killing the plant. I also quite often find spider webs leading form plants near by. What might it be and can the plant be saved?

Answer
Sounds like Euonymus Scale.
Euonymus scale (Unaspis euonymi): This is the most common and most serious pest found on euonymus. The protective armor covering of an adult female euonymus scale is dark, oyster-shaped and about 1/16-inch in length. Adult males are very small, winged insects that leave their narrow, white armored covering for mating. The eggs laid by the female are yellow and found beneath the female抯 covering. When the eggs hatch, the crawlers (immature forms) move around before forming their own protective covering. Males typically outnumber females. With a heavy infestation, clusters of white males can be easily seen on leaves and stems. Initial symptoms of euonymus scale infestation are yellow spots on leaves. With a heavy infestation, branches and possibly the entire plant may die.

Prevention and Control:  The following Euonymus species are resistant to euonymus scale: E. alatus 慍ompactus?and E. fortunei 慉cutus.? Consider using these in new plantings. Euonymus scale is difficult to control. With light infestations, scale can be scraped off by hand and destroyed. Pruning out heavily infested branches is helpful. Avoid using insecticides unless the plant is very valuable and in serious danger from scale. Insecticides will often kill the naturally occurring enemies of scale.

Adult scales are relatively protected from insecticides by their waxy covering. Their immature forms, called crawlers, are susceptible, however. Horticultural oil (Bonide All Season Spray Oil, Ferti-lome Scalecide, Green Light Horticultural Oil Spray, or Ortho Volck Oil Spray) can be used as a dormant spray before new growth begins in the spring. It kills many adults and eggs by smothering them. Spray again when crawlers are present in the spring.

Monitor the crawler emergence with sticky cards, double-faced tape wrapped around a branch, or by putting an infested shoot or leaf into a baggie and watching for crawler movement. Crawler activity often coincides with the flush of new plant growth in the spring. However, some scale species may have overlapping generations with an extended crawler emergence period.

If insecticides are necessary, the following are effective against crawlers: acephate (Ortho Japanese Beetle Killer), malathion (Ferti-lome Mal-A-Cide or Hi-Yield Malathion Insect Spray), cyfluthrin (Bayer Advanced Garden Power Force Multi-Insect Killer), and carbaryl (Sevin 50WP or Ferti-lome Carbaryl Spray). Make sure that crawlers are present before using them. Apply three sprays at 10-day intervals. As with all pesticides, read and follow all label instructions and precautions