Origin:
Possibly a native insect in North America.
Biology:
This scale can be found throughout North America where host plants are grown. Severe infestations can stunt the growth of the plant and lead to premature loss of leaves. A female may deposit several thousand eggs that hatch in early spring. The crawlers then move about to new locations to feed until late summer when they molt to the second instar. This stage then moves back to narrow twigs, creates a wax shell over itself, and overwinters in this stage.
Identification:
This odd looking scale is dark brown and strongly raised off of the twig. The highest point is slightly offset from the center as a distinct rounded ridge, and the wax scale then narrows and flattens toward each end. The scale ranges from 2 to 6 mm in length, depending on its age, and it may have some amount of white wax over it.
Characteristicts Important to Control:
Dormant or summer oils may be effective in killing the scales, as well as contact insecticides applied when the first instar crawlers are present, which may be from early to late summer. Applications need to concentrate on terminal twigs and foliage. Determining the effectiveness of the control effort is difficult. The wax scales adhere tightly to the plant, even when the actual insect is no longer living, and very close examination beneath the scale may determine whether the insect itself is dead or alive.
