Survival and post embryonic development of the oriental armyworm,Mythimna separata (Wlk.) was studied on 5 host plants, viz sorghum, maize, sugarcane, Johnson grass and napier grass during winter months (15 November to 7 March) under laboratory conditions. Variations in different parameters like larval survival (10·3–60·3%), size of larvae (7·33–29·67 mm), larval weight (25·5–493·1 mg for 26 days old larva), size of pupa (15·0–16·49 mm), pupal weight (184·9–249·5 mg for 2–4 days old pupa), pupation (3·3–38·9%), developmental period (74·8–109·8 days) and moth emergence (3·4–50·0%) were significant on different foods. Low temperature and humidity conditions during experimental period resulted in complete mortality of female pupae reared on napier grass, Johnson grass and maize whereas in case of males 60–100% moths were crippled winged. However, adults emerged on sorghum and sugarcane foods were normal except 28·7% males in sorghum were crippled. Total growth index was also higher on sugarcane (0·45) and sorghum (0·24) indicating their suitability in carrying over of winter pest population.