Infested fruit has a spotted or mottled appearance because of a small red inflamed area surrounding each scale. Scale infestation on apple branch. Hosts San Jose scale attacks apple, pear, plum, sweet cherry, apricot, peach, nectarine, quince, currant, gooseberry and Osage orange. As temperatures warm to about 50 degrees F in the spring, the insect resumes growth. About the time trees are in bloom, two forms of scale can be found.
Females continue to reproduce for about six weeks.
The young scales are very small, yellow mite-like insects with six well developed legs and two antennae. They are called crawlers because they crawl over the surface of the tree. Within 24 hours they find a place that is suitable to them, where they insert their slender thread-like mouthparts through the bark or fruit or leaf, and begin to suck sap. Soon after settling down to feed, crawlers shed their skin, legs, and antennae, and appear as flattened yellow sacks attached to the bark or fruit. As they continue to grow, the body secretes wax that hardens to form the characteristic San Jose scale.