The effect of temperature on the development and fecundity of Sancassania polyphyllae fed on tissues of Polyphylla fullo larvae was studied at 15, 20, 25, 30, and 35 +/- A 1A degrees C and 65 +/- A 10% RH in a dark incubator. Mean developmental period of immature stages decreased significantly with increasing temperatures from 15 to 30A degrees C. Developmental periods at 30-35A degrees C were not significantly different. The estimated lower developmental thresholds of the various immature stages ranged between 10.1 and 11.5A degrees C. The thermal constant for the egg-to-female adult was 93.5 degree-days. The pre-oviposition, oviposition, and post-oviposition periods and female longevity were significantly longer at 15A degrees C than at higher temperatures. Mean total and daily fecundity were the highest at 25A degrees C, which were significantly different from those obtained at 15, 20 and 30A degrees C. The net reproductive rate (R (0)) was the highest at 25A degrees C (588.3 a (TM) Euro/a (TM) Euro). The longest mean generation time (T (0)) occurred at 15A degrees C (36 days) and the shortest occurred at 30A degrees C (9.2 days). The highest intrinsic rate of increase (r (m)) for S. polyphyllae was observed at 25 (0.61 a (TM) Euro/a (TM) Euro/day) and 30A degrees C (0.62 a (TM) Euro/a (TM) Euro/day).