New pesticidal crops are taking advantage of advances in geneticengineering. For example, corn has been engineered to express Bt proteinsthat are toxic to the European corn borer. These crops are effective pestmanagement tools for United States growers. However, there is concern thatpests will develop resistance to these crops resulting in the increased useof more hazardous pesticides. The purpose of this paper is to develop astochastic dynamic bioeconomic simulation model to help guide regulatorypolicy designed to mitigate the threat of resistance to new pesticidal crops.The model is used to evaluate the insect resistance management guidelinesmandated by the United States Environmental Protection Agency for theuse of Bt corn in the Midwestern United States.