We apply chemical pesticides to crops to kill nuisance organisms that reduce yield. Nowadays, pesticides are artificial rather than natural compounds, so they are properly called toxicants rather than toxins. Inherently harmful, pesticidal toxicants can detrimentally affect the non-target organisms that inhabit agroecosystems. We are particularly concerned when pesticides affect non-target organisms that are beneficial species which provide ecosystem services, such as pollinators and natural enemies. Relative to their potency, modern insecticides are applied at higher rates than DDT, which properly should cause alarm and prompt careful management (Figure 10.1).