Laboratory-derived life tables were used to determine the effect of delaying mating of adult female koa seedworm, Cryptophlebia illepida (Butler) (Lepidoptera: Tortricidae), 4 and 6 d on population growth rates. Leslie matrices were developed from the life tables and used to project the effects for approximately four generations. Delay of mating caused a decrease in population growth rate and also resulted in asynchronous population cycling between control (1-d delay) and the delayed treatments. By the fourth generation, the control population began to increase 10 and 14 d before the 4- and 6-d delay treatments, respectively. Increasing the mortality of females during the first 7 d of adult life resulted in a greater reduction of the populations where mating was delayed than in the control populations. This result suggests that even at relatively low levels of natural enemy mortality, there is a synergistic effect when mating is delayed. The implications of these effects on mating disruption management programs are discussed.