Abstract
The cold-hardiness of the Silver-Y moth, Autographa gamma, at the egg, larval and pupal stage was compared with that of the Asiatic Common Looper, A. nigrisigna. In each stage, nearly all individuals died at chilling (0°C, 100% RH) for 10 to 30 days without hardening (10°C for 1 day and then 5°C for 5 days). However, if hardened, more individuals survived chilling for more days in both species. This effect was most remarkable in A. gamma. Hardened third-instar larvae of A. gamma survived chilling for 120 days at a rate of 1.4%. By contrast, no individuals of hardened A. nigrisigna survived chilling for 90 days.
