The use of estimated 2.27 million metric tons of pesticide applied worldwide - as well as the use of biological and other non-chemical controls - pests continue to destroy enormous amounts of valuable food and fiber. Since 1945 the overall use of synthetic pesticides in the United States has grown 33 fold although the amounts of particular herbicide, insecticides, and fungicides used have fluctuated with time, due in large part to changes in agricultural practices. In addition, the toxicity and biological effectiveness of these newer pesticides have in created at least 10-fold. Losses from pests have not, however, shown a concurrent decline. Since 1942, losses from weeds have decline slightly, due to improved weed control practices. Losses from plant pathogens have increase slightly. The share of crops lost to insects, however, has grown from 7% to 13% during the last 40 years despite the immense increase in the amount and toxicity of synthetic insecticides. This increase can be expl