The mite species Cheyletus eruditus was reared on eggs and immatures of the acarid mite, Acarus siro (Oudemans) at 20 and 30 °C. All biological aspects of the predator were significantly affected by the temperature. The incubation period, life cycle and longevity of males and females were significantly increased when the cheyletid mite fed on A.siro eggs at 20 ºC. in comparison with 30 ºC. Incubation period of C. eruditus significantly differed between the male and female and further more between the different temperature degrees. The longest incubation period recorded when the males fed on the immature of A .siro 8.3 days at 20 °C and the shortest period 4.4 days when the male fed on eggs of A. siro at 30 °C. The female life cycle durated 30.7 and 19.1 days on eggs of A.siro at 20 and 30°C, respectively, changed to 24.8 and 14.4 days when the males fed on the same prey, respectively, On the other hand, when the immatures of A. siro were used, C. eruditus life cycle lasted 32.6, 24.7; 19.9 and 15.1 days for the females and males, respectively. The adult female longevity of C. eruditus differed and reached to the highest level when  fed on eggs of A. siro at 20 °C recorded 42.9 days and showed the shortest  period when the males  fed on immature stages of A.siro (14.0 days).The generation period of C. eruditus female durated 36.1 and 21.2 days when fed on eggs of A.siro at 20 and 30 °C, changed to recorded 36.6 and 22.5 days when the mites fed on immature stages of A.siro. Fecundity was significantly higher when the female fed on eggs of A.siro record 49.92 eggs at 30 °C and decreased to recorded the lowest number of deposited eggs at 20 °C when the females fed on immature stages of A.siro (33.0 eggs). During the longevity and life span  of C. eruditus females, the mites consumed 282.7 and 344.8 eggs of A.siro at 20 C respectvely, changed to record 130.7 and 147 eggs of  A. siro in case of male individuals at the same temperature. While at the female consumed 236.0 and 268.0 immatures of A.siro and male consumed 150 and 158 immatures of A.siro at the same temperature. When eggs of A. siro introduced as prey for C. eruditus at 30 ⁰C, the female of the predator consumed 340.5 and 436 and males consumed 220 and 247 eggs during longevity and life span, changed to record 315.0 and 387 immatures of A.siro in case of adult female of the predator and 150 and 163.6 immatures in case of male individuals in the same temprature.