Abstract: European red mite is a serious problem of apple in Himachal Pradesh .At present more than 80 % orchards have been found infested with European red mite. It sucks cell sap from leaves which resulted into poor quality of fruits. Present studies were undertaken to see the effect of environmental factors e.g. temperature and relative humidity on the buildup of mite population in the apple trees at RHRS, Mashobra. The predicted optimum temperature and relative humidity was calculated by using Beta model is 21.45oC and <85% respectively.