The flight patterns of the peach twig borer Anarsia lineatella (Zeller) (Lepidoptera: Gelechiidae) were studied in two important and representative regions of peach production in Northern Greece. In order to determine the seasonal occurrence of the species, adult male moth flight was monitored from April till October (2005-2006) using 8 pheromone traps. The observation areas were located at the regions of Veria (lat. 40.32 degrees North) and Velvendos (lat. 40.16 degrees North). The first flight was observed from early May to early June in Veria and from late May to mid June in Velvendos. The 2nd and 3rd flights were observed from late July to early August and from late August to late September in both regions. The degree-days required for the first generation (431 Veria, 371 Velvendos) were fewer than for the 2nd (661 Veria, 504 Velvendos) and the 3rd generation (675 Veria, 506 Velvendos). A lower threshold temperature of 100 C was used in calculating daily day-degrees from March 1st. All the above data are valuable for the development of prediction models and for decision making in order to achieve better timing of treatments. Considering the increasing interest of biorational insecticides where precise timing of treatments is extremely important, degree-day models could be a useful tool for improving their efficacy in IPM.