Kocourek, F., Beránková, J., Streinz, L., & Webster, A.D. 2000 San José scale (Quadraspidiotus perniciosus Comst.) male flight pattern monitoring by means of pheromone traps.. Acta Horticulturae No. 525: 407-409.

Notes: [Proceedings of the International Conference on Integrated Fruit Production, Leuven, Belgium, 27 July-1 August 1998, Muller, W., Polesny, F. & Verheyden, C. (Eds.)] Based on studies in the Czech Republic, the date on which the first generation of crawlers of Q. perniciosus [Diaspidiotus perniciosus] on apple 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.