The San Jose Scale is a destructive pest of fruit trees, especially for apples, peaches, and plums. This pest is known by several synonyms, including Quadraspidiotus perniciosus, Scale insect, and San Jose Shielback. The San Jose Scale is a tiny armored scale insect that feeds on the sap of the fruit trees and causes leaves to yellow and drop prematurely, reducing the tree's productivity and fruit quality. To control these pests, gardeners often turn to horticultural oils or insecticides. The San Jose Scale can be a challenge to manage, but early detection and timely control measures can help protect fruit trees from this pesky pest.