Abstract: The threshold temperature and thermal constant of various stages of the meadow moth(Loxostege sticticalis L.) were determined in the laboratory. The threshold temperatures for egg, larva, pupa, adult and whole generation weere 14.3℃, 12.7℃, 11.6℃, and 10.5℃, and thermal constants for them were 30.5, 190.7, 158.3, 96.7 and 531.2 day-degrees, respectively. Although the calculated values of threshold temperature were snmewhat different from the values actually measured, the number of predicted generation based on above results were consistent with those actually observed in various geographic regions in China. According to the computation of thermal constants, the generation number of meadow moth occurred annually appeared decreasing with the increasing of latitude. There was annually 1generation in the areas northern to the annual isotherm line of 0℃, 2-3 generations to 0-8℃,and 3-4 generations to 8-12℃. Analysis of population dynamics of the meadow moth in various regions revealed that this insect caused damage mostly in the 2-3 generation region bythe first generation occurring from May to July.

Key words: Loxostege sticticalis——threshold temperature——thermal constant, generation.