Combined effects of constant temperature (15–35°C) and relative humidity (50–90%) on longevity and total duration of life cycle of Tetrastichus pyrillae Crawford, one of the most common egg parasitoids of the sugar-cane leaf hopper, Pyrilla perpusilla Walker were determined and are discussed. Influence of the temperature both on the longevity and the developmental duration of this egg parasitoid was highly significant while the relative humidity did not produce any marked change. Average longevity of males decreased from 5.89 to 1.06 days and that of females from 9.60 to 1.04 days in response to corresponding rise in test temperature from 15 to 35 ± 1.5°C. Mean duration of its life cycle also declined from 40.5 to 9.8 days as the rearing temperature was raised from 15 to 30 ± 1.5°C. Developing parasitoid died, without attaining adulthood within its host eggs, at or above 32.5°C.
