Quadraspidiotus perniciosus
Pest description and damage Scale insects are small (less than 0.125 inch in length) soft insects that live beneath waxy scales. These insects are often identified by the shape and size of their scales, the description of adult males and females, immature crawler stage, color of eggs, and host plant preferences. San Jose scale is a pest of many ornamental and wild trees in the PNW, particularly in hot, dry climates. San Jose scales can be differentiated from other scale insects by the hard, gray to black, and cone-shaped scale covering the insect. The scale is about 0.06 inch in diameter and has a tiny white knob in the center with a series of grooves or rings around it. Twigs with infested bark are roughened, rather than smooth, and twig death may occur. Often there is a purple halo on the bark around each scale. At high population densities, fruit is also infested and displays these dark halos about the scales. Crawlers are flat and yellow and common in June and again in August to September.
For biology, life history, monitoring and management
See:
Cherry, flowering (Prunus)-San Jose scale
See "Scale insect" in:
Management-chemical control
See Table 1 in: