Cumulative effects of constant temperature (15–35°C) and relative humidity (50–90%) on longevity and total duration of the life cycle ofOoencyrtus papilionisAshmead, a common egg parasite of the sugarcane pest,Pyrilla perpusillaWalker, were determined. The influence of temperature on the longevity and developmental period of the egg parasite was highly significant, and relative humidity also produced marked differences in longevity and life cycle duration. Average longevity of males decreased from 4.15 to 1.22 d and that of females from 10.39 to 1.68 d in response to increasing temperature from 15 to 35.5 ± 1.5°C. Mean life cycle duration also declined from 40.68 to 9.28 d as the rearing temperature increased from 15 to 30 ± 1.5°C. No development occurred within the host eggs at or above 32.5°C.