The Unnatural Enemy of the Potato
The Crusade to Keep Colorado Potato Beetles as Far Away From Potatoes As Possible - Part I
In the early morning of June 6, 1820, American entomologist Thomas Say set off on horseback towards the Rocky Mountains, unsure of what he might find.
With him was a team of seven men—naturalists, artists, topographers, and one journalist—hand-picked by the U.S. government to conduct the first scientific survey of the west. The mission was called “Long’s Expedition of 1820,” so named after team captain and army topographer, major Stephen Harriman Long.
Say had already made a name for himself among the country’s top entomologists and was there primarily to observe and catalog the wildlife of the Western United States alongside fellow naturalist Titian Peale. Crossing the Great Planes and then heading down the Red River towards Arkansas at a pace of 30 miles per day, the two of them would collect approximately 60 prepared skins of “new or interesting” animals and a few thousand insect specimens, nearly 800 of which were previously undiscovered. There was plenty to find in the unexplored territory of the American heartland. But our story begins in present-day Colorado, where Say would happen upon an insect that was desperate to make a name for itself.
Decemlineata, the Colorado beetle, the ten-striped beetle, the ten-striped spearman, the ten-lined potato beetle, the potato bug, or—as it’s more commonly known today—the Colorado potato beetle was discovered by Thomas Nuttle in 1811 before it was formally described by Thomas Say in 1824. At about ten millimeters in length, the beetle could easily rest atop your thumbnail with plenty of room left to roam. But what it lacks in size it makes up for in appetite.
“There is a new and very destructive enemy of the potato,” opens entomologist Benjamin Dana Walsh in “The New Potato Bug and Its Natural History,” the first volume of a monthly bulletin called The Practical Entomologist, published by the Entomological Society of Philadelphia in 1865. In the 20 years since Say published his initial description of the insect, the Colorado Potato Beetle had made a home for itself among the potato crops of farmers across the midwest and as far as Illinois. Walsh tracks the beetle through Colorado and Nebraska, warning the rest of the nation’s potato farmers that this particular beetle “will probably travel onwards to the Atlantic, establishing a permanent colony wherever it goes, pushing eastward at the rate of 50 miles a year.”
One rancher in Atchison, Kansas, said of the beetle’s tremendous presence on his ten-acre farm that year “that they would almost cover the whole potato vine, eating up everything green on it.” In Iowa, another farmer laments the beetle’s voracious appetite, saying of his crops that, “as soon as they were out of the ground… [the beetles] devoured them as fast as they were up.” Kil Patrick, also from Iowa, similarly notes, “I took more than a gallon of bugs this morning from eleven tows of potatoes eight rods long.” I’m not exactly sure what that means, but it doesn’t sound ideal.
The source of the Colorado potato beetle’s name is no mystery, but it is slightly misleading. The beetle’s natural host plant is in fact not the potato but a species of nightshade known colloquially as the Buffalo bur—or Solanum rostratum scientifically. Endemic to the United States and Mexico, the Buffalo Bur has kept the potato beetle and its closest relatives well-fed for millions of years. Limited by the range of its host plant, the potato bug likely would have happily remained in the shadow of the Rocky Mountains for another million years. Wouldn’t that have been boring.
So, what happened? How did the beetle begin its rapid geographic expansion? And why had it gone undetected by farmers until the 19th century? Here too, Walsh provides an answer. S. Rostratum is a member of the botanical family Solanaceae, which also features the likes of the tomato, the eggplant, a weed called the horse-nettle, and—you guessed it—the potato. Operating under the assumption that S. Rostratum is the natural food of the insect, Walsh provides a hypothesis that has since become accepted as fact:
In process of time, civilization marched up to the Rocky Mountains—potatoes were planted in Kansas and Nebraska and Colorado—and the insect discovered that one species of Solanum was about as palatable as another. Having thus acquired a taste for potato leaves, it would naturally spread eastward from potato patch to potato patch till it overspreads Iowa and finally overleaps the Mississippi into Illinois.
Walsh goes on to predict that at its current rate of progress, the pest would reach the East Coast in about 14 years. As it turns out, his estimate was far too generous.
No later than 1875, the new potato bug made it to the beach. On September 14, eggplant farmer J.J. Dean of Brooklyn, NY, recalls interacting with the beetle at Coney Island. “The beach for miles was covered with them—the hummocks and sand-hills which comprise the greater part of the Island were literally alive with them,” he says. “I am however puzzled by the fact that so many millions of them desert the fertile fields of Flatbush and Gravesend and steer for the barren acres of Coney Island. They appear to have an irresistible tendency to travel East, and are only stopped by the waves of the Atlantic Ocean.” This too would be a miscalculation.
While Walsh had simply cataloged the eastward march of the Colorado Potato beetle, the succeeding naturalists whose attention the insect garnered would adopt a slightly more involved approach. Charles Valentine Riley, often regarded as the father of modern entomology, published two works on the Colorado potato beetle within a relatively short window which demonstrate this shift in attitude: The Colorado Potato Beetle and Other Insect Foes of the Potato in North America (1876) and The Colorado Beetle: With Suggestions For Its Repression and Methods of Destruction (1877).
In the former, Riley continues charting the beetle’s path of destruction, carefully detailing the modes of transportation by which the beetle migrates from “potato patch to potato patch,” which seemed implausible to many scientists at the time. Generally, the Colorado potato beetle migrates by air in flying swarms or by land in marching hoards. But it’s also been known to traverse expanses of water. In one example, Riley explains, “as we know from experience, many insects that are entirely unknown on the western side of Lake Michigan are frequently washed up along the lake shore at Chicago… often alive and in good condition.” On multiple accounts, the insects could wash ashore in “such countless numbers” that the stench of their decomposing bodies could be smelled “for miles around.” There’s no doubt, according to Riley, that the potato bug’s appearance across the North East and Canada on either side of the Great Lakes is in part thanks to the insect’s ability to “survive a sufficient length of time to be drifted alive to Point Edward.” It seems that, once the potato bug had gotten its first taste of potato, it wouldn’t be denied a second. But that didn’t stop Riley from trying.
Once one of the cheapest products of the farm, the potato had at this point become a luxury product. Many farmers altogether abandoned their efforts to grow potatoes on account of looming potato bug infestations, and the crop’s price rose to $2.00 per bushel by the mid 1870s (about $48 today). The Colorado potato beetle’s unchecked aggression could no longer be tolerated. In Riley’s second full-scale study of the insect, he shifts gears, coaching the world’s farmers in the art of entomological warfare. Before diving into his suggested “methods of destruction,” he begins with a two-fisted warning: “Transportation to Europe has become a demonstrated possibility.” He fears that there is no natural barrier—land, air, or sea—which can stop the beetle’s spread. But perhaps, armed with the right combination of weapons, humans could put Pandora back in her box.
In true Colorado Potato Beetle fashion, the Colorado Potato Beetle made it to Liverpool, England, in 1877, before Riley’s book made it off the press.
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Looking forward to part 2!