Abstract: From 1984 to 1988, nine generations of paddy borer, Tryporyza incertulas, were observed at Sihui county, Guangdong Province and the survival curves of each generations were plotted based on the life table data. The hashest mortality occured at the boring stage of young instar larvae (65.77-80.26%), and the type of survival curves appeared to be Slobodking IV. The k-values in all life tables show that k₉ is highest and k₅ is the next. Key factor analysis were conducted with Varley's diagram and Podoler's regression methods respectively. The first key factor was the mortality for transmigration in old instar larvae stage and the second was the invasion mortality in young instar larvae stage.

Key words: Tryporyza incertulas, Life table, Key factor