The effect of season on the reproductive performance of Monochamus carolinensis (Olivier) reared in pine logs was investigated by constructing fertility tables for each of 39 jack pine, Pinus banksiana Lamb., logs that differed only in the season that they were cut. Population parameters that measured survival and reproduction of M. carolinensis, including the intrinsic rate of increase ( r ), were compared among 3 seasonal cohorts. The intrinsic rate of increase and associated population parameters of beetles that emerged from logs cut during spring were significantly higher than for beetles that emerged from logs cut during summer and autumn. Only minor differences were found between beetles emerged from summer and autumn logs. The nutritional value of phloem and cambium tissue of pines is highest during the spring months. We hypothesize that seasonal differences in the nutritional quality of logs caused the observed differences in M. carolinensis survival and reproduction.