Populations of the bollworm, Helicoverpa zea (Boddie), and the tobacco budworm, Heliothis virescens (F.), were monitored with pheromone-baited wire cone traps on the Red River Research Station from 1986 to 2005. Data are presented on population variation and changes observed during the sampling period for the months of May through August. Bollworm moths made up 87.8, 79.0, 82.7, and 63.5% of the total number of male moths captured in May through August, respectively. Overall, 76.3% of the male moths captured from May though August were bollworms. The abundance of bollworms in pheromone traps indicated considerable variation on a yearly and monthly basis. The number of bollworms captured in traps and an analysis of variance provided no evidence that the introduction of Bt cotton in 1996 had any significant effect on bollworm abundance at this location. However, abundance of tobacco budworm has been decreasing since approximately 1993–1994. Analysis of variance confirmed that abundance of male tobacco budworms caught in traps was significantly less post-Bt cotton (1997–2005) compared with the pre-Bt cotton period (1986–1996). However, the analysis also indicated that abundance of tobacco budworms had been decreasing significantly before commercialization of Bt cotton in 1996. The decline did not seem to have increased since the introduction of Bt cotton although bollworm abundance still is decreasing. The decline in tobacco budworm abundance in this study seems to have begun before the introduction of Bt cotton. It is still possible that the duration and significance of the decline is related in some way to the introduction of Bt cotton in 1996, or the decline could be the result of normal variation and/or population cycles of a length that cannot be ascertained due to the length of the sampling period in this study. Regression analyses indicated that numbers of tobacco budworm in any given month were a good predictor of abundance in subsequent months. This was not true for abundance of bollworm.