Dispersal of adult tortricid moths between habitats may have important consequences for pest management in orchards, but little is known about how ßight parameters are affected by environmental conditions during preimaginal development. The inßuence of changing temperature and photoperiod (both singly and in combination) as well as of larval crowding and food deprivation were investigated in Cydia molesta Busck (Lepidoptera: Tortricidae), a species that has been found to disperse after peach

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... vest and colonize pome fruit orchards. Comparative assessments of ßight parameters were made on a computer-linked ßight mill and life history traits were evaluated. A signiÞcant increase in ßight performance was correlated with preimaginal exposure to decreasing photoperiod. In addition, pupal development was delayed and larger individuals emerged, but preimaginal survivorship was reduced. Decreasing and increasing temperature regimens and increasing photoperiod did not inßuence adult ßight. Larval crowding was associated with increased ßight, but the differences were not statistically signiÞcant. Food deprivation was associated with accelerated preimaginal development, lower pupal weight, less fecund adults, and reduced ßight. We propose that the main factor eliciting dispersal in this tortricid is decreasing photoperiod.