Studies were conducted with codling moth, Cydia pomonella L., to evaluate the mating status of male and female moths in apple, Malus domestica (Borkhausen), orchards treated with and without sex pheromone dispensers. Laboratory studies first examined the effect of multiple mating of male and female moths on female fecundity and egg fertility. Females that had mated three times had a significantly higher fecundity than singly mated moths. Sequential mating by male moths had no effect on the fecundity of female moths or egg fertility. However, male moth age did impact female fecundity, with significantly fewer eggs laid after mating with virgin 1- versus 3-d-old males. The mean size of the first spermatophore transferred by males was significantly larger than all subsequent spermatophores. Classifying spermatophores based on size was used in field sampling to categorize the mating status of the female’s partner. The proportion of mated females with small spermatophores (partner had previously mated) was significantly higher in treated versus untreated orchards. The proportion of female moths caught in traps baited with pear ester that were virgin was low (≤0.26) in both treated and untreated orchards. The proportion of females with more than one spermatophore was low (≤0.06) in treated orchards all season and during first moth flight in untreated orchards (0.11). Nearly one third of female moths, however, had more than a single spermatophore in untreated orchards during the second moth flight. The potential impacts of multiple mating and delayed mating by male and female codling moth on the effectiveness of sex pheromones are discussed.