The development rates of Myzus persicae and Lipaphis erysimi were determined under a series of constant, alternating and natural temperature regimes. The results showed that ( 1 ) the relationships between temperature and development rater under constant conditions follow a logistic curve with lower and upper boundary; (2) except at high temperature range (for Mpersicae. >28℃, for L.e-rysimi, >30℃) where under constant conditions mortality increasesed and development rate decreased rapidly, temperature fluc...