Great Basin Naturalist


A review of published and unpublished data for the predatory mite Typhlodromus mcgregori in Utah and southern California apple growing areas is presented to summarize its role. Typhlodromus mcgregori was not found resistant to pesticides and, although usually present with Bryobia rubrioculus, only when Aculus schlechtendali was also present was there significant predation on B. rubrioculus. Aculus schlechtendali was considered the primary host and B. rubrioculus secondary for T. mcgregori. Typhlodromus occidentalis was always found associated with Tetranychus spp. and often with Eotetranychus and Pronematus ubiquitus in unsprayed orchards.