The present study was completed during three successive cot­ton-growing seasons (1996-1998). Monitoring the changes in the popu­lation density was achieved when number of male moths of Pectinophora gossypiella (Sound.) was considered based on pheromone trap catches. The obtained results revealed that P. gossypiella, after emerging from the diapausing stage, underwent two distinct broods; the first had two generations, while the second possessed 4-5 overlapping field genera­tions. The 2 generations of the first brood emerged during the period from half of April till half of June and proved to be suicidal since the fruiting structures suitable for infestation are not available. The 4 gener­ations of the second brood extended during the period from early of June to the end of December. The number and durations of generations were estimated based on both zero of development (11.97°C) and the accumulated thermal units needed for completing one generation (487 DDS). The present field and laboratory studies introduce valuable infor­mation to establish a profitable model when adopting I.P.M. programs.