Adults could only live and reproduce to their full capacity at temperatures between 20°C and 30°C. At 15°C the females laid no eggs, the adult life span was relatively short and the reproductive capacity of females kept at 35°C was low. The thermal histories of the flies had no apparent effect on their later reactions to temperature in any of the parameters tested. The viability rates of S. calcitrans eggs exposed to temperatures between 10°C and 40°C exceeded 84%, but 45°C was lethal. The optimum temperatures for incubation of the eggs was 30°C. Pupae of S. calcitrans seemed to tolerate temperatures between 20°C and 30°C, but their mortalities increased markedly outside this temperature range. Tests showed that pupal mortalities increased linearly with increasing periods of exposure to a temperature of 15°C.