The red mason bee (Osmia rufa L.) is a univoltine solitary species of the Osmia genus. This bee is reared on a commercial scale and used as a managed alternative pollinator. We intended that the results of our study would improve the management of this bee so as to synchronise their flying period with the blooming of crops. In the spring, we moved newly occupied nests of the red mason bee to a laboratory and placed them in incubators. Immature development was examined at three constant temperatures, 20°C, 25°C, and 30°C. Selected nests were opened to monitor the subsequent developmental stages. The remaining bees were wintered in nests stored at cool temperature (4°C). In April, we removed the insects from the nests and began incubation at 25°C to establish the emergence time of adult individuals. To determine the survival rate of adult bees, we moved the emerged specimens to cages, where they were fed and kept until death. Temperature increase generally reduced immature development time. But this tendency was not observed in the prepupal stage. During ontogeny the highest mortality rate was observed in wintering adult insects at developmental temperatures of 25°C and 30°C. Bees developing at constant temperatures emerged faster during spring incubation in comparison to those developing in natural conditions. Constant developmental temperatures decreased the survival rate of females as post-emergence adult insects. The survival rate of males was lower at the developmental temperature of 30°C.
