The present study was carried out at Fayoum Governorate during 2005 and 2006 seasons under field condition. The temperature is an important environmental factor on, rate of development, survival and in any other biological and ecological aspects for the American Bollworm Helicoverpa armigera. Seasonal abundance of the insect population and predication of field generation throw a light on the temperature influence on development in the field. The data showed that the American Bollworm Helicoverpa armigera had five generations on the prevailing host plants during the period from March 1^st to November 1^st in addition to overwintering generation, which the moths emerged during March from the hibernation. The predicted peaks of generations could be detected when the accumulation thermal units 557.5 dd's. The males of the overwintering generation reached the real and predicted peaks at the same time (during the April for the two investigated seasons). The predicted peaks for the other five generations detected earlier or later +3 to -3 days than the observed peaks. The expected peaks and the corresponding expected generations for American bollworm could be helpful when IPM control tactics are considered.