Bt corn is unlikely to harm monarch butterflies.
It was planted on more than 20 million acres last year, and the majority of scientists and growers believe it represents a significant advance over traditional chemical insecticides for the control of pests that threaten yields. The benefits of Bt corn, including Monsanto's YieldGard , are significant. It has been proven to increase yields by 5 to 10 percent, sometimes more, by effectively controlling European corn borers and other insects that cause significant crop damage. It also suppresses populations of these insects locally, reducing the severity of their attack on other kinds of crops, and it is more specific and more environmentally friendly than any chemical insecticide. Yet, when John Losey, Ph.D., of Cornell University published the results of one laboratory experiment in a letter to the journal Nature last May suggesting Bt may cause harm to the monarch butterfly's larvae, the safety and continued use of Bt corn pollen was suddenly in the spotlight.