Based on adult captures on baited red sphere traps and larval fruit infestations, the apple maggot (AMF), Rhagoletis pomonella (Walsh), exhibits a bimodal emergence pattern in western North Carolina. The first period of adult activity occurs from late May through mid June, and the second from mid July through August. Potential reasons for this bimodal activity pattern are unknown, but may be attributed to apple cultivar on which larvae feed, variation in AMF diapause requirements, and/or a genetically linked trait. To test the hypothesis that apple cultivar affects the developmental rate of AMF larvae, and thus the time when they enter and complete diapause development, maggot-infested ‘Golden Delicious’ and ‘Delicious’ apples were collected in September 2003, held outside in buckets filled with sand, and pupae were collected in January 2004. Pupae were then placed into several groups that differed by the by the length of time that diapause conditions were simulated. The adults were counted and sexed as they emerged after removal from diapause conditions to determine if the fly emergence pattern differed between cultivars. To test the hypothesis that “early” and “late” emerging flies are the have a different diapause development requirement, a group of pupae collected from infested apples were subdivided in eight simulated diapause intervals, ranging from 0 to 52 wks. The adults were counted and sexed as they emerged to determine if there was a difference in the percentage of individuals emerging at various times after removal from diapause conditions.