Now is a good time to carefully inspect ornamental trees and shrubs, as well as fruit trees, for scale insects.
Scale insects come in two types, armored scales and soft scales.
Armored scales live under a separate, hard, wax shell, which they secrete as they develop. The shell is usually rather flat and may be well camouflaged and very hard to detect. These scales are usually less than 0.1 inch in size. The scale may be round or oyster-shell shaped and can be found on the leaves, twigs, or branches. Soft scales are larger, 0.1 to 0.2 inches in size, and are usually oval or round and stick up from the plant.