Similar to the California Red Scale, the San Jose Scale (Quadraspidiotus perniciosus) is a pest insect of tree fruits (mainly apple, pear, and peach). It is a true bug of the order Hemiptera. And similar to the California Red Scale, it forms a waxy protective covering, which makes it very difficult to attack with insecticides. They are most vulnerable early in spring, and one of the orchard growers I talked to said he was going to saturate the trees with oils next week as a way to suffocate the scale insects.
This is what the infestation looks like on his apple trees.
The main impact of the scale insect is to reduce the yield of the fruit trees and the quality of the fruit, so it can result in a loss of income for the orchard growers if it is not properly controlled.