The effects of pheromone trap design and trap placement on collections of male San Jose scale,Quadraspidiotus perniciosus(Comstock), were studied over a 3-year period in California, Oregon, and Washington. Open (tent) trap designs were more efficient than closed traps, with small tent traps as good as larger tent traps. Trap placement in the north or east tree quadrants consistently produced the highest collections of male scale, but these catches are probably influenced by local meteorological conditions at the time of male flight. Collections of male scale increased as trap height increased into the upper tree canopy. Comparisons of the three pheromone isomers showed isomer SJS-3 generally to be more attractive than either SJS-1 or SJS-2. Pheromone dispenser load rates of 100 to 1,000 μg of SJS-2 showed no significant reduction in scale collections with 300- to 1,000-μg rates, compared with fresh 300-μg loads after 8 weeks of field exposure. Fresh, 300-μg loads were significantly better than all dispensers aged 16 to 19 weeks in the field