Periodic mass rearing and harvesting of specific life stages are analyzed based on the theories of both the age-specific life table and the age-stage, two-sex life table. Formulae for the calculations of the optimal discard age and harvest rate are derived. For practical applications, the use of thermal summation to manipulate the developmental time of specific life stage is suggested. The model is demonstrated using life table data ofOstrinia furnacalis(Guenée).