San jose scale (Quadraspidiotus perniciosus Comst.) male flight pattern monitoring by means of pheromone traps

摘要

The date on which the first generation of crawlers starts to migrate can be calculated as the sum of effective temperatures of 400 day degrees (dd) above 7.3~ C, calculated from the date on which the first males have been found in the pheromone traps. The date indicates the optimum period for timing of insecticide application.