Abstract: Using the propertional value of temperature standard deviation δ_x to average temperature , the rearing date of Masson pine caterpillar, Dendrolimus punctatus Walker was analyzed. The results showed temperature coefficient isan important index influencing the development of caterpillar. Within favorable temperature range, at the same developmental stage, the average temperature among the Masson pine caterpillars were close to each other, but thetemperature coefficient differesgreatly from each other. While the temperaturechanges strongly, the larvae develop slowy; while the temperature changesweakly, the larvae develop quickly. There is no significant correlation betweenthe number of generation and the annual average temperature and the decadeaverage temperature higher than 10℃; but there is very sinificant negativecorrlation between the number of generation and the coefficient of decadeaverage temperature higher than 10℃.

Key words: Dendrolimus punctatus Walker, Temperature coefficient, Development