Abstract: The pink bollworm Pecdnophora gossypiella is an important pest of cotton in Central China. It breeds three generations a year and its mature larva passes over winter. The life tables of its natural population were constructed from 1978 to 1988 in Jianghan Plain and the average values of demographic constants of the first, second and third generation were determined as follows: The survival rates were 3.23 ±1.07, 4.01±1.83, and 1.46±1.09; and the exponential equations were Y₁= 61.66 e0.58x Y₂=142.47e^-0.73x and Y₃=146.68e^-0.80x, where x=stage of development, the type of curve appeared to fit in with type A of Price(1975), which gave over 80% self mortality from egg to the mature larva in each generation. The population trend indices were 1.12, 2.03 and 0.45. The second generation had the highest index in each year which caused eventually heavy damage to the cotton bolls and resulted in a rapid increase of population density of the third generation. The average and maximal numbers of eggs produced per female moth were 34.8/253, 50.66/235 and 30.79/293. Sex percentage of the female moths were 54.6%,54.8% and 51.1%. The natural instananeous rate of population increase r were 0.0390, 0.0430 and 0.0026. Net replacement rate R were 4.39, 4.43 and 2.04. Mean length of a generation Twere 38, 37 and 276 days. Finite rate of increase were 1.0398, 1.0411 and 1.0026 times. Population doubling time t were 18,17 and 267 days respectively. The population fluctuation was essentially affected by the self mortality of the intrusive borers in each generation and the overwintering Iarvae, which could be called as the key stages of pest mortality relevant to population density.

Key words: Pectinophora gossypiella——natural population——demography