Pest description and damage The mature scale is approximately 0.125 inch long, hard-shelled, pinkish (alive) or gray (dead) in color, and usually elongated and slightly curved like an oyster or mussel shell. Oystershell scale is found on trunks, branches, and twigs. This scale occurs less frequently on the leaves and other plant parts. Scale infestations often are limited initially to isolated colonies on single branches or twigs. Newly emerged crawlers look like bright white pimples on the bark.
For biology, life history, monitoring and management
Ash (Fraxinus)-Oystershell scale
See "Scale insect" in:
See Table 1 in: