Low-density, sleeve cage releases of Sasajiscymnus tsugae Sasaji and McClure were conducted in two hemlock woolly adelgid (HWA), Adelges tsugae Annand, infested environments in western North Carolina. At both sites, predators reproduced successfully inside sleeve cages and dispersed to other parts of release trees following release cage removal. Sampling techniques have been unable to detect long-term predator establishment at either site to date. However, evidence of predator activity based on changes in HWA abundance and improved hemlock health may serve as early indicators of success for adelgid biological control programs utilizing S. tsugae.