In October 1854, a government entomologist was inspecting some farmland outside the town of Ottawa, in northern Illinois, when he came upon a disturbing scene in a cabbage patch.
The large outer leaves of the vegetables were "literally riddled with holes, more than half their substance being eaten away." With each step he took around the ravaged cabbages, tiny swarms of little ash-gray moths rose from the ground and flitted away. This was, it appears, the first record in the United States of the diamondback moth, an invasive pest that in its larval form shows a fondness for cruciferous vegetables. By the late 1800s the moths were chewing through the leaves of cabbages, brussels sprouts, collards, and kale from Florida to Colorado.
To fight this invasion, farmers started bombarding their fields with primitive pesticides. This worked. Or seemed to. It killed most of the moths, but those that survived the poison reproduced, and the population bounced back stronger than ever. For decades, one pesticide after another failed as the moths evolved to withstand it. Even the grievously toxic DDT was no match for the diamondback. Beginning in the late 1950s, agriculture experts started to abandon the idea of eradication and adopted a new strategy. Farmers would leave the moths alone until their numbers exceeded a certain threshold, and only then would they deploy pesticides. Remarkably, this helped. The moths did not die out, but the pest could be managed and crop damage held in check.
When Robert Gatenby heard this history of the diamondback moth in 2008, he immediately latched onto it. Gatenby is not a farmer nor an agronomist nor a fan of cruciferous vegetables—in fact, he deeply loathes brussels sprouts. He is a radiologist by training and heads the radiology department at the H. Lee Moffitt Cancer Center in Tampa, Florida. But unlike your typical doctor, he is also obsessed with the evolutionary principles put forth more than 150 years ago by Charles Darwin. The story of the diamondback moth appealed to Gatenby as a useful metaphor for his own project—one concerned not with crops but with cancer.