1493_ Uncovering the New World Columbus Created - Charles C. Mann [132]
Insects have bothered farmers since the first planting of crops in the Neolithic era. But large-scale industrial agriculture changed the incentives, so to speak. For millennia the potato beetle had made do with the buffalo bur scattered through the Mexican hills. By comparison, an Iowa potato farm—hundreds of orderly rows of a single type of a single species—was an ocean of breakfast. By adapting to the potato, the beetle could command many more resources for reproduction than it had ever possessed before; its numbers naturally exploded. So did those of other pests—the potato blight is a notable example—that were able to take advantage of the same opportunities. Each of the massive new farms was a fabulous storehouse of riches for the species that could exploit it.
Those farms were ever more similar, a hallmark of the Homogenocene. Because growers planted just a few varieties of a single species, pests had a narrower range of natural defenses to overcome. If a species was able to adapt to the potatoes in one place, it would not have to adapt to those in others. It could simply jump from one identical food pool to the next—a task that was easier than ever, thanks to modern inventions like railroads, steamships, and refrigeration. Not only did industrial agriculture present insects with a series of rich, identical targets; these faster, denser transportation networks made it ever easier for faraway species to exploit them. In 1898, L. O. Howard, Riley’s successor, calculated that at least thirty-seven of the seventy worst insect pests in the United States were recent imports (he wasn’t sure of the origins of six others).
As this cover illustration on an 1877 number of the London newspaper supplement Funny Folks suggests, British farmers feared the arrival of the Colorado potato beetle. (Photo credit 6.7)
The late nineteenth century was, in consequence, a time of insect plagues. The boll weevil, slipping over the border from Mexico, wiped out so much cotton in the South that the governor of South Carolina proclaimed a day of public prayer and fasting to fight the bug. The cottony cushion scale, an Australian insect, swept through California’s citrus industry. A European import, the elm leaf beetle, ravaged elm trees in U.S. cities; Dutch elm disease, introduced from Asia despite the name, would arrive later and more or less wipe out all elms east of the Mississippi. Returning the favor, the United States exported phylloxera, an aphid that wrecked vineyards in most of France and Italy.
For the wine industry, the solution was discovered by Riley, the Entomological Commission head: grafting European grape vines onto U.S. grape roots, which resist the aphid. For decades afterward, most French and many Italian grapevines had American roots. For the potato, the solution was more consequential: Paris Green.
Paris Green’s insecticidal properties were supposedly discovered by a farmer who finished painting his shutters and in a fit of annoyance threw the remaining paint on his beetle-infested potato plants. The emerald pigment in the paint was Paris Green, made largely from arsenic and copper. Developed in the late eighteenth century, it was common in paints, fabrics, and wallpaper. Farmers diluted it heavily with flour and dusted it on their potatoes or mixed it with lots of water and sprayed.
Paris Green was a simple, reliable solution: buy the pigment, mix in flour or water according to the manufacturer’s instructions, apply it with a sprinkler or dust box, and watch potato beetles die.