AbstractSurvivorship curves for the pre-adult stages of Pieris rapae (L.) on kale in Massachusetts exhibited two patterns. Early season generations showed a linear decline with mortality in all stages, whereas late season generations showed reduced losses in larval instars 2-4 and a concentration of mortality in the fifth instar. Ratios of direct measurement of recruitment of P. rapae and its parasitoid Apanteles glomeratus (L.) to their first larval and egg-plus-larval stages, respectively, indicated that losses to parasitism for five host generations were 86·1, 9·1, 58·O, 71·7 and 40·3% for the 1985 third generation and the 1986 first to fourth generations. Patterns of percentage parasitism within single generations were determined by higher rates of mortality in parasitized than healthy older larvae (instars 3-5) and, in some cases, by higher rates of host than parasitoid recruitment towards the end of the generation.