Critical thinking

Ask three questions about the passage from Silent Spring that I am sharing here. Answer one of your own questions in a short paragraph (4-8 sentences)

In Chapter 15, "Nature Fights Back," Carson discusses some unintended consequences of using pesticides where biological pest control was already working. (Biological pest control involves finding and encouraging the natural predators of pest insects. For more information check out the video below where she mentions the program Carson discusses in this passage.)

". . .consider the situation in the citrus groves of California, where the world's most famous and successful experiment in biological control was carried out in the 1880's. In 1872 a scale insect that feeds on the sap of citrus trees appeared in California and within the next 15 years developed in to a pest so destructive that the fruit crop in many orchards was a complete loss. The young citrus industry was threatened with destruction. Man farmers gave up and pulled out their trees. Then a parasite of the scale insects was imported from Australia, a small lady beetle called the vedalia. Within only two years after the first shipment of beetles, the scale was under complete control throughout the citrus-growing sections of California. From that time on one could search for days among the orange groves without finding a single scale insect.

Then in the 1940's the citrus growers began to experiment with glamourous new chemicals against other insects. With the advent of DDT and the even more toxic chemicals to follow, the populations of the vedalia were wiped out. Its importation had cost the government a mere $5000. Its activities had saved fruit growers several millions of dollars a year, but in a moment of heedlessness the benefit was canceled out. Infestations of the scale insect quickly reappeared and damage exceeded anything that had been seen for fifty years. . . Now control of the scale has become enormously complicated. The vedalia can only be maintained by repeated releases and by the careful attention to spray schedules, to minimize their contact with insecticides." (256-7)