Seasonal activities of the peach fruit fly, Bactrocera zonata (Saunders) and the Mediterranean fruit fly, Ceratitis capitata Wiedemann were studied on grapes and guava orchards during the two successive fruiting seasons of 2014 and 2015 using white Jackson traps. The obtained data revealed that B. zonata showed differently three slight peaks of activity on grapes orchard during the first and second seasons; while on guava orchard it exhibited three to four distinct peaks of activity yearly. C. capitata showed two annual peaks of activity on grapes and guava orchards. B. zonata and C. capitata populations were significantly higher on guava orchard than that on grapes one during the two seasons of investigation. On other hand, B. zonata population was significantly higher than that of C. capitata on the two crops during the first and second seasons. Also, there were inversely correlations between B. zonata and C. capitata populations on grapes and guava orchards during the first and second seasons; however, the correlation coefficient values (r) between their populations were negative. According to the competition equations of Lotka-Volterra, there was a comparative co-existence between B. zonata and C. capitata on grapes and guava orchards at the area of study.