Ecological studies on the apple rust mite Calepitrimerus baileyi Keifer was conducted for one year in an abandoned Anna apple orchard in  Egypt Population dynamic of the eriophyid apple prey was affected by climatic conditions, and vertical distribution, and about  11 generations were recorded whole year. Leaves at middle levels of apple cultivar were found  preferable to the mite feeding than  those at the top and bottom. C. haileyi successfully developed to adult stage when reared on leaf discs from soft lateral  apple branches. At 16 and 37°C, the adults began to  slow down activity and then  died. It was able to  develop at temperature  between 23-35oC and 65% R.H.  Adult life cycle and longevity decreased with increasing temperature.  Fecundity was highest at 35°C and averaged 23 eggs per  female.  Life table  parameters  showed  that  the  intrinsic  rate  of natural  increase  (r_m)  increased  with temperature increase to a maximum of 0. I 58 at 35°C. Population of C. baileyi multiplied I 5.94 times in a generation  time f  17.47 days at 35°C and recorded 8.79 times  in  a generation time  of 25.8 days at 23°C  under laboratory conditions.