The population dynamics of the 3rd and 4th generations of Helicoverpa armigera in both cotton and corn fields were surveyed systematically at Fengxian County, Jiangsu Province, in 1998. And their survival and development rates were compared by means of life table method. It was indicated that the life span from egg to the 4th instar of the 3rd generation was 4d shorter in corn fields than in cotton fields and most rapidly development occurred when their eggs were laid during the male heading stage of co...