Laboratory studies were conducted to assess the effect of constant temperatures (15, 20, 25, 30, and 35°C) on life history traits of peach twig borer, Anarsia lineatella Zeller (Lepidoptera: Gelechiidae). Developmental rate, survival, longevity, and fecundity were studied in environmental chambers from individuals reared on peach, Prunus persica L., twigs until adulthood. Temperature-dependent relationships of various developmental events were characterized, and applied models were evaluated. Total developmental time ranged from 20.4 d (30°C) to 124 d (15°C). Lower developmental thresholds for egg-to-adult development assessed to 11.2 or 11.8°C, according to a linear weighted regression or the reduced major axis method, whereas development required on average 400 degree days (DD) or 424.4, respectively. Survival was substantially reduced at lower (15°C) and higher (35°C) temperatures. First-instar larvae exhibited higher sensitivities during development in all treatments. Mean longevity ranged from 12.1 d (35°C) to 45.8 d (15°C) and from 10.4 d (15°C) to 50.3 d (35°C) for females and males, respectively. A significantly higher number of eggs was laid at the moderate temperatures (126.9 at 25°C), whereas at the extremes, females laid the fewest (40.4 and 26.3 at 15 and 35°C, respectively). A new model, based on a β type distribution function, fitted on the temperature-dependant developmental data to predict population dynamics. Relative accuracy of the above-mentioned formula was validated using root mean square error (RMSE), index of agreement (d) and the mean square error quotient (E_1,2) with respect to a proved model.