Postdiapause development rates and$\bar V$O2were determined inTrypoxylon politummaintained outdoors and in the laboratory under constant temperatures of 8, 14, 18, 22, 26, 30, and 34°C. This wasp may begin postdiapause development outdoors when the mean daily temperature is as low as 6–7°C if the temperature rises above the theoretical development threshold of 14.9°C for some time during the day. The wasp does not develop at constant temperatures of ≤ 14°C, or at ≥ 34°C. The rate of development increases linearly with temperatures from 18 to 26°C, but declines at 30°C. Prepupal respiratory rates increased significantly at 22°C; the rates of propupal and pupal stages increased at 26°C. Optimal development, with regard to energy utilization (respiration) occurred at 22°C.$\bar V$O2and age exhibit a catenary relationship at temperatures at which development occurs. The total oxygen consumed during development exhibited a linear relationship with temperature from 22 to 30°C. Thermal accumulations acquired in completing development at 18, 22, and 26°C are very similar. The outside group's thermal acquisition was only 80% of the total at 18–26°C. At 18°C, development appeared to be complete, but wasps failed to eclose and died within the cocoon after reaching the adult stage