Cold hardiness of cotton bollworm from nine geographic regions in China was inves-tigated in the laboratory and field. The supercooling points (SCP) of non-diapausing and dia-pausing pupae of different populations ranged from - 19. 13℃ to - 18. 16℃ and - 19. 53 ℃ to- 19.03℃, respectively, generally, SCPs of geographic populations increased with the de-creased latitude. The differences of 50% lethal times (LT50s) indicated that survival of dia-pausing pupae was significantly higher than that of non-diapausin...