AbstractPheromone trapping studies from 1979 to 1981 showed that there were two periods of San Jose scale,Quadraspidiotus perniciosus(Comstock), male flight activity annually in western New York apple orchards. Spring flight, which resulted from overwintering black caps, began at ca. 94–140 degree-days (base 10 °C from 1 March) and occurred during bloom in the apple varieties studied. First generation crawlers emerged at ca. 360 degree-days. Second generation crawlers emerged at ca. 890

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... ays and were active throughout September. Regression analyses showed a logistic relationship between crawler density and fruit infestation, and inverse linear relationships between pheromone trap catches and San Jose scale infestation levels within trees.