Sepedon fuscipennisLoew was reared in the laboratory under constant temperature regimes to determine the effect of temperature on several life history features. Developmental and oviposition rates are greatest at 30°C. Total survival of the immature stages is greatest at 33°C. The intrinsic rate of increase is positive over the 15–33°C range, and it peaks at 30°C where rm= 0.137 day−1. Adult longevity increases as temperature decreases. Total fecundity is highest at 21°C. In the laboratory, most adults live beyond the age at which they contribute significantly to the intrinsic rate of increase.S. fuscipennisis a typical polyvoltine species exhibiting imaginal facultative diapause. Diapause is characterized by cessation of ovarian development, cessation of spermatogenesis, and hypertrophy of fat bodies. Both temperature and photoperiod influence diapause induction in the sensitive and responsive adult stage.