The temperature response of the American bollworm Heliothis armigera (Hubner), was studied at constant temperature of 25 C and 17.5 C. The temperature threshold for development of eggs, larval, pre-pupal, pupal and from egg to adult emergence stages were 14.17, 12.63, 14.81, 14.65 and 13.87 C respectively, and the thermal requirements necessary for development of previously mentioned stages were 30.33, 199.14, 26.45, 146.93 and 403.49 day-degrees above the temperature threshold. The mean number of eggs/female, % hatchability, % pupation and % emergence were higher for the 25 C than the 17.5 C.However mean weight of pupae on lower degree is more than the higher temperature.