In order to study the biodiversity of fruit flies (Diptera, Tephritidae) in two pomegranate agroecosystems in M’sila (North East of Algeria) and to monitor the dynamics of their populations, we used two types of trapping between October 2017 and November 2018. The first type is based on McPhail traps baited with the pheromone trimedlure and is exclusively intended for the study of the dynamics of the populations of the ceratitis. The second is mass trapping based on a network of olipe traps baited with diammonium phosphate, intended to study both the biodiversity of other fruit flies captured by this trap and their population dynamics. The inventory of Tephritidae revealed the presence of six species namely: Acanthiophilus helianthi (Rossi, 1794), Bactrocera oleae (Rossi, 1790), Ceratitis capitata (Wiedemann, 1824), Dacus frontalis (Becker, 1922), Tephritis nigricauda (Loew, 1856) and Tephritis praecox (Loew, 184 4). We note the rediscovery of D. frontalis 22 years after its first report. Two species of Tephritidae marked their dominance in the traps of the massive trapping network, namely: T. praecox and B. oleae. The use of the density of flies per trap and per day was assessed by calculating the FTD: number of flies per trap per day which constitutes a tool for indicating the level of the population and its monitoring, for phytosanitary alerts related to fruit flies. The FTD values of the fruit fly attracted by the McPhail trap according to the field trips were between 0.1190 at the end of June and 10.7083 (peak) at the beginning of October for the Boukhmissa orchard and between 0.0159 at the end of June and 3.1429 (peak) at the end of October for the Ouled Addi orchard.