Development of the cucurbit fruit fly Dacus ciliates (Loew) (Diptera: Tephitidae) was studied at constant temperatures (15, 20, 25 and 30 ± 1 ̊C). The development of immature stages was accelerated by rising of tested temperatures. Development stages average of eggs, larvae, pupal and pre-oviposition period ranged between (31.13 and 3.47), (37.07 and 5.80), (30.27 and 7.20) & (33.13and 5.73) days on 15 and 30 ̊C, respectively. Also, total immature stages ranged between 98.47 and 16.47 days on 15 and 30 ̊C, respectively. Whereas, Generation period ranged between 131.60 and 22.20 days on 15 and 30 ̊C, respectively. Additionally, adult females survived slightly longer than males, also life span, and sex ratio. While the estimated (t_o) threshold temperatures stages eggs, larval, pupal and pre-oviposition period were 15.05, 13.39, 10.64 and 13.11 heat units (U.T.) at 15, 20, 25 and 30 ̊C ±1 ̊C, respectively. Based on 30 ̊C estimations are required to complete the development of all immature stages. Also, Thermal requirements (K) D.D.'s were estimated to be 58.35, 97.07, 133.58 & 103.81 for eggs, larval, pupal and pre-oviposition periods at 15, 20, 25 and 30 ̊C ±1 ̊C, respectively. And development for one generation required 386.17 D.D′s, The study showed that with the identification of threshold temperatures (t_o) and thermal units (K) for generation calculated nine expected generations in the field they: two  generations in spring, four  generations in summer, two  generations in autumn, one generation in winter.