The present study was conducted in Beni-Suef Governorate under field conditions during the seasons of 2005 and 2006. Results indicated that the population of the American bollworm moths, Helicoverpa armigera (Hübner) had four peaks starting from the 3rd week of May until the 2nd week of September during the two tested seasons. The highest number of moths was recorded during the end of July and the whole August which being 120 & 154 moth/trap/35 days and 150 days after cotton planting in both seasons, respectively. The predicted peaks of generations could be detected when the accumulated thermal units recorded 558.18 DD's. The predicted peaks for the detected four generations varied from +2 to -3 days from the observed peaks. For better prediction of the American bollworm the period between the observed and expected peaks should be positive and as short as possible when early preparation of pest control materials are of great important, consequently it could be helpful when IPM control tactics are considered.