All stages of Tetranychus urticae Koch (Acari: Tetranychidae) were subjected to short periods (0-16 hours) of exposure to low temperatures (0, -5 and -10 degrees C), followed by rearing at 20 degrees C. Adult survivorship was greater than that of the juvenile stages, but there was no difference between survival rates of the two sexes; duration of exposure had more effect than the actual temperature experienced. Many surviving juvenile mites did not successfully complete their development to adult: 8 hours at 0 degrees C was sufficient to prevent almost all development. The longevity of surviving treated adults was reduced, but there was little reduction in the adult longevity of surviving treated juvenile stages. Both duration and level of low temperature exposure affected the fecundity of treated adults. Treatment at the deutonymph stage-also affected the fecundity of the resulting adults. Male fertility was unaffected by low temperature exposure, except possibly at the longest exposure durations. Development of the surviving treated immature stages was retarded; the temperature experienced had more effect than the duration of exposure.