Nonchemical, environmentally friendly quarantine treatments are preferred for use in postharvest control of insect pests. Combined high temperature and controlled atmosphere quarantine treatments for phytosanitary fruit pests Macchiademus diplopterus (Distant) (Hemiptera: Lygaeidae) and Phlyctinus callosus (Schöenherr) (Coleoptera: Curculionidae) were investigated to determine the potential of such treatments for quarantine security. Field-collected, aestivating M. diplopterus adults and P. callosus adults were treated using a controlled atmosphere waterbath system. This system simulates the controlled atmosphere temperature treatment system (CATTS) used to control a number of phytosanitary pests in the United States and allows for a rapid assessment of pest response to treatment. Insects were treated under regular air conditions and a controlled atmosphere of 1% oxygen, 15% carbon dioxide in nitrogen, at two ramping heat rates, 12 and 24°C/h. Treatment of both species was more effective under both heating rates when the controlled atmosphere condition was applied. Under these conditions of controlled atmospheres, mortality of P. callosus was greater when the faster heating rate was used, but the opposite was true for M. diplopterus. This could be due to the physiological condition of aestivation contributing to metabolic arrest in response to the stresses being applied during treatment. Results indicate that the potential for the development of CATTS treatments for these phytosanitary pests, particularly P. callosus, is promising.