Beginning with a brief introduction to the evolution of modern ideas of pest control, we document the idea of the “pesticide treadmill.” Countering the pesticide paradigm, biological control is noted as a simple ecological fact, best thought of in agroecology as autonomous pest control, as popularized in the so-called Morales effect. We then present a detailed example emerging from our ecological work in Mexico. We end the chapter with an analysis of the need for action with limited knowledge, always a problem when attempting to apply ecological knowledge (which is itself invariably limited, an acknowledgment of the dialectical approach). The necessity of applying rules of thumb is thus acknowledged.