San Jose scale is an old and well-known insect pest of deciduous fruit trees and ornamental shrubs. It flares up from time to time to focus attention on its potency as a destroyer of these woody plants. Although long experience has established that dormant oil sprays are effective in controlling this and other species of scale insects, the patterns of insect and disease control are now rapidly evolving to accommodate new organic pesticides. The quest for optional pesticides and more convenient periods to apply them for San Jose scale requires detailed knowledge about the habits and tendencies of its populations. The investigations described in this report were designed to supply needed data on the behavior of this scale insect, particularly under conditions encountered in the interior valley of California.
