Two spotted spider mites, Tetranychus urticae Koch the most important pests of strawberry, have developed resistance to chemical pesticides. We investigated the effects of high carbon dioxide atmospheres on two-spotted spider mites and strawberry plants just before transplanting. Percent mortality of adult female mites, young eggs 24 h after laying , and old eggs 48-72 h exposed to 60% CO 2 at different temperatures 25, 30, and 35 C was evaluated over time. Mortality of all spider mite stages increased with exposure duration at each temperature, and the time required to achieve 100% mortality decreased as temperature increased. Exposure to 60% CO 2 at 30 C for 16 h was 100% lethal to every developmental stage tested. Furthermore, 24 h of 60% CO 2 treatment did not induce external damage or adversely affect flowering of the primary flower clusters on strawberry plants. In a large-scale test of elevated-CO 2 atmospheres, the two spotted spider mite population was greatly suppressed relative to untreated fields, and strawberry plants remained healthy. Thus, our findings suggested that CO 2 treatment could be used to propagate spider-mite-free plants in strawberry nurseries and enhance strawberry integrated pest management systems.