The relationships between temperature and each of the rate of development and life table parameters for Tetranychus urticae infesting cotton in Minia, Egypt were studied under field conditions. Two mathematical models were tested for their accuracy to represent these relationships. Results clarified the important effects of temperature on the rate of development, fecundity and population increase. Lower threshold temperatures, upper thermal thresholds and the thermal constants were determined for different developmental stages. The linear regression model was better than the sigmoid curve in representing the relationship between temperature and the rate of development, as the deviations between the actual and the calculated values were negligible. The moderately high temperatures proved to be the most favorable for both development rates of different stages and growth rates of the population. Using the developed models, in the second season, it was easy to determine the timing of the acaricide application to achieve good results and to reduce the number of sprays, the control cost and the environmental pollution leading to maximizing the role of the natural enemies.