Biological studies showed the following: 1. - Tenuipalpus granati proved to Ье thelytokous. Females passed through а larval and two nymphal stages before being adults. 2. - The incubation period lasted for 8.5, 4.3 and 5.4 days, and the period of immature stages required 20.6, 13.3 and 26.6 days, dшiпg spring, summer and autumn, respectively. The female life cycle lasted for 29.1 days at 23.60С and 55.4 % R.H., 17.6 days at 30.00 С and 63.5 % R.H., 32.0 days at 27.80С and 62 % R.H., during the previous mentioned seasons, respectively. Autumn females, hibernated till early spring (about 149.4 days where they began to deposit their eggs. The adult female lived for 9.7 days and laid 18.2 eggs in summer, and survived for 17.5 days and deposited 16.7 eggs in spring. Elgharibi variety did not suit the mite development and fecundity, while Romey red was highly favourable.