Growth is stunted and flowers are not produced. Scales usually appear in clusters. Prune out and destroy heavily infested canes. Spray plants with an insecticide. To prevent scale infestation, spray plants with horticultural oil in early spring.
Holes appear in unopened rosebuds.
Leaves and stems may also have holes or may be chewed off. Caterpillars, the larvae of moths and butterflies. Most are yellow or green and up to 1 inch long. Spray with Bacillus thuringiensis , called Bt, a bacterium fatal to caterpillars but harmless to plants and other animals. If caterpillars return to your garden every spring, Bt can be sprayed in anticipation of the problem.