Öz This study was conducted at peach and nectarine orchards in Adana and Mersin provinces, between the years 2005–2007. In this study, the adult population fluctuations of peach twig borer (Anarsia lineatella) was determined by using pheromone traps in two nectarine and one peach orchards. The pest did not reach high population levels in the peach orchard in Adana/Mıdık and in nectarine orchard in Mersin/Alifakılı. However, high population densities of A. lineatella occured in the nectarine orchard in Adana/Hadırlı. Adults emerged on the first week of April in all three years and their activity continued until November depending on years. During this period, at least 2 and at most 4 flight periods were seen which the first flight was in April-May intervals. Adult population generally reached to the peak level (17 June 2005: 229 adults/trap; 26 June 2007: 57 adults/trap) in June. The occurence of 4 to 5 adult peaks in three years implies that the pest has 4 to 5 generations in a year. The pest caused serious shoot damage in the trial orchard. However, in this orchard where the early ripening species were cultivated, fruits free of A. lineatella damage can be grown without insecticide application.