The life history of Phytoseiulus longipes Evans was studied at four different constant temperatures to construct life tables. The intrinsic rates of natural increase were .210, .366, .549, and .393; net reproductive rates, 27.97, 31.15, 47.80, and 13.80; and mean generation times, 25.95, 11.64, 9.42, and 7.79 days at 20, 25, 30, and 35°C, respectively. The durations of the preoviposition, oviposition, and post-oviposition periods, as well as adult longevity, declined with increasing temperature. Mean total and mean daily fecundities generally increased with rising temperatures. Mean total developmental time declined curvilinearly with ascending temperature; however, speed of development had a strong positive linear relationship with increasing temperatures. Threshold temperature of development and thermal constants for different immature stages were calculated. Comparisons of the life histories of P. longipes, P. persimilis Athias-Henriot, and T. occidentalis Nesbitt were made. The egg hatching of P. longipes under different combinations of relative humidities and temperatures was also studied. At any given temperature, percent eclosion increased with rises in percent relative humidity