ABSTRACT
Work in the 1970s on pesticide resistance made important progress, but it included an important simplifying assumption. Pest infestations were treated as exogenous, as if the level of infestation facing a farmer in any growing season depended only on the number of pests left alive the previous year plus some random factors; all other farmer decisions were irrelevant. This approach made the analysis easier because it limited the farmer's decisions to the choice of how much pesticide to use each season. More pesticide this year meant higher yields this year and fewer pests to control next year but also more resistance in the pest population. The optimal path was driven by the relative strength of these forces.
