Biological studies on the predatory mite, Phytoseiulus macropilis (Banks). Showed that the female lived longer than of the male; whereas female and male longevity averaged 14.72 and 11.5 days, respectively. The predator efficiency of consumed immature stages of Tetranychus uticae Koch, increased during the predator developmental stages as well as the adult female and male consumed 77.4 and 27.5 immatures of T.uritcae, respectively. At cold storage of P.macropilis eggs at 10 and 5oC, respectively when the stored eggs transferred at 25oC. The biological aspects of the predator P.macropilis after cooling storage of its eggs at 5oC, respectively when the stored eggs transferred at 25oC. The biological aspects of the predator P.macropilis after cooling storage of its eggs at 5oC for one week, compared with the biological aspects of P.macropilis at 25oC indicated that female longevity decreased to 8.9 + 1.74 days comparing with 14.5 + 1.5 days for control. Female fecundity reduced in cooling treatment, which the number of deposited eggs per female was 19.36 + 6.6 eggs and it was 45.4 + 4.99 eggs per female in control.