Dirty white caterpillars, about 3/4-inch long with 2 rows of black spots running down their backs, feed in groups within webbing over the ends of branches. As they consume leaves within the webbing, they enlarge it to include more leaves. Eventually, whole branches or shrubs may be covered.
Control euonymus caterpillar with an insecticide labeled for this pest. Break up webbing with a garden hose, then spray it with as much pressure as possible.