Hoyt, S.C., Westigard, P.H., & Rice, R.E. 1983 Development of pheromone trapping techniques for male San Jose scale (Homoptera: Diaspididae).. Environmental Entomology 12: 371-375.

Notes: Quadraspidiotus perniciosus; studies conducted in Calif., Oregon, and Washington; advantages and disadvantages of different traps; collection of species increased as trap height increased into upper tree canopy.