Locust (27 page)

The importance of alfalfa in the story of the Rocky Mountain locust became a matter of contention almost as soon as the theory was proposed. As Brett’s work was being published, Robert Pfadt was coming onto the grasshopper scene. Born in Erie, Pennsylvania, in 1915, the thirty-four-year-old assistant professor had recently arrived at the University of Wyoming. He had developed an interest in grasshoppers while a student in Wyoming, continued these studies during his doctoral program at the University of Minnesota, and carried this interest back to the faculty position at his alma mater. Pfadt continued his work on grasshoppers for half a century, establishing a record of practical research that convinced the university administration to replace him with another acridologist after he retired in 1984—which is how my position came to be. His work in grasshopper ecology was not focused on the Rocky Mountain locust, but he was drawn into the tale of this creature through his eminently practical work on its kin.

In 1949, Bob published a lengthy work on his experiments concerning the role of food plants as factors in the ecology of
sanguinipes
. The relation of alfalfa to the health of grasshoppers was not quite so straightforward as Brett has suggested. It was true that this plant was a very poor food on which to rear nymphs of
sanguinipes
. If provided only with alfalfa, barely one in five nymphs survived to
adulthood, and they weighed about half as much as grasshoppers fed on dandelion, their most healthful food.
⁵

But Bob was one of the most careful and meticulous researchers of his day. He invariably valued quality over quantity, such that a single comprehensive paper was preferred to a dozen pieces of fragmented science. So, Bob conducted a separate series of experiments to discover whether alfalfa was indeed detrimental to adult grasshoppers. Much to his surprise, when healthy adults were fed alfalfa, versus other food sources, they had superior longevity and egg production. Alfalfa, it seems, was the grasshopper equivalent of a glass of Merlot with dinner: a fine dietary component for grown-ups but not for children. And this finding provided the key to a paradox. Despite Brett’s assertion that alfalfa was deleterious, entomologists had often observed that
sanguinipes
flourished in alfalfa fields. Bob attributed the infestations of this species in alfalfa to their consumption of weeds that infest the crop. Even a modest amount of dandelion or bromegrass in the diet of developing nymphs could offset the deleterious effects of alfalfa.

Bob not only cast doubt on whether alfalfa was invariably detrimental to
sanguinipes
(and, by inference, to
spretus
) but also questioned, on two other grounds, the validity of Brett’s claim that the planting of this crop could account for the disappearance of
spretus.
First, he noted that we knew very little about the plants on which
spretus
originally depended, so nothing could really be said about whether alfalfa had actually replaced anything of importance to the locust. Even if alfalfa was harmful to the insect—and this was not unambiguously the case—the effect would be marginal unless the crop had replaced a vital food source.

And this argument led to his second concern, which both reflected the contemporary thinking and shaped much of the subsequent discussion regarding the locust’s disappearance. Bob pointed out that no matter what the effect of alfalfa, it simply did not exist on a sufficient scale to have impacted
spretus
throughout its range. Even a deadly
poison—and alfalfa fell rather short of this—would need to have been spread over an area much larger than the nooks and crannies of the landscape filled with alfalfa. This crop requires a great deal of water, and although it was abundant in irrigated valleys, the range of the locust was immense and included vast areas of dry uplands where prairie grasses could not be replaced by thirsty alfalfa fields. A decade later, Gurney fully endorsed Bob’s contention, noting that he’d also found no evidence of “any pronounced range-plant changes in Montana during the 1860s, 1870s, or 1880s, so far as the general disappearance or replacement of plant species is concerned.” It appeared that poor Charles Brett had it wrong again. Not only was
sanguinipes
incapable of giving rise to
spretus,
but alfalfa fields seemed to have nothing whatsoever to do with the disappearance of the locust.

With the dismissal of the “alfalfa theory,” a consensus began to form on the fate of the Rocky Mountain locust. In the 1950s, the environmental movement was dawning, and ecologists were thinking in terms of large-scale anthropogenic effects—continental, even global, changes—on other species and ecosystems. And this way of perceiving the growing conflicts between humans and nature fostered the conceptual agreement among entomologists that the disappearance of the locust, a species that stretched across millions of square miles, must have been caused by an environmental change of commensurate scale. Although the precise mechanism causing the decline of the species was not apparent—just as nineteenth-century evolutionists did not understand genetics—the fundamental nature of the process was obvious. The challenge was to find a sweeping change that was concurrent with the locust’s disappearing act.

When one thinks of a life form sweeping across the West, locusts are not likely to be the first creatures that come to mind. Rather, the iconic image of the bison fills this legendary place in the lore of the prairies. Although we associate bison with western grasslands, the range of these animals included almost every state, as well as northern Mexico and western Canada. In 1839, Thomas Farnham traveled
through a herd of bison along the Santa Fe Trail—for three days. Farnham could see bison stretching fifteen miles in either direction along his forty-five-mile passage, so he estimated that the herd covered more than a thousand square miles. Some thirty years later, Major Richard I. Dodge, traveling along the Arkansas River, encountered the largest reliably measured bison herd. This outpouring of hide and hoof was fifty miles long and twenty-five miles across, and later calculations estimated a population of 4 million animals. These animals were the furry counterparts of the waxy locusts on the continent. Attempts to estimate the total population size of either creature are fraught with speculative assumptions, but the efforts are revealing.

The peak number of bison has been calculated in various ways. Early estimates were based on extrapolations from hunting records. Modern approximations of carrying capacity—a measure of the number of creatures that can be sustained by a particular resource base—set the average sustained population density at 26 bison per square mile throughout their range. Ecologists have also tried to apply historical observations in refining crude guesses from nineteenth-century hunters. Given that the population estimates come from such a diversity of sources, it is somewhat remarkable that they all fall within the same range. Our best guess is that there were 30 to 60 million bison in North America, prior to European settlement.

Estimating the peak number of Rocky Mountain locusts is an equally dicey affair. But let’s take the outbreak of the 1870s and presume that half of the reportedly infested area actually had locusts present at any given time. If so, then these insects were present across an area of 500,000 square miles (about twice the area of Texas). The carrying capacity of rangeland for modern-day grasshoppers is around 10 individuals per square yard. Using this figure—which is probably quite conservative, as we’re considering the locust during an outbreak—we’d end up with 15 trillion insects, or a couple thousand locusts for every person currently on the earth.

Now then, to put the bison and locust on equal footing, we need some common units. Ecologists tend to prefer biomass—the number of kilograms, pounds, or tons of living tissue. Let’s assume that the average bison weighed in at five hundred pounds, using the figure for a
juvenile as a reasonable compromise between a mature male weighing a ton and a newborn calf weighing thirty-five pounds. If there were 45 million bison, then there were somewhere around 11 million tons of critters scattered over the continent. As for the locusts, let’s assume a weight of half a gram per locust, which is the size of
sanguinipes
. Given 15 trillion insects, their collective biomass would have been about 8.5 million tons. So, bison and locusts had similar, and rather phenomenal, masses of herbivorous tissue. And both were very nearly gone by the turn of the nineteenth century.

 

Bison were quickly extirpated in regions where they were not particularly plentiful in the first place and humans were relatively numerous. By 1819, there were virtually no bison east of the Mississippi River, and by 1840 these creatures had been wiped out to the west of the Rocky Mountains. However, massive herds still roamed the plains, where people were thinly distributed. These millions of creatures were ultimately doomed by a tragic conspiracy of sociology, economics, and politics. The beginning of the end of the bison came with the end of beaver. That is, by the 1830s, unfettered trapping had decimated the beaver populations, and the American Fur Company and the Hudson Bay Company switched from purchasing beaver pelts to bison hides. With the emergence of this market came the professionalization of hunting. However, bison carcasses are absurdly cumbersome to handle, and the coastal markets were far from the Great Plains. So the demand for bison flesh was restricted to tongues, the prized cut of meat, and millions were shipped to market—with the rest of the carcasses left to rot on the prairie.

With the building of the transcontinental railroad came the means of shipping immense quantities of people into the West and staggering quantities of bison out to the East. Although bison meat was popular in the East after the Civil War, the death knell for these animals came with the development of new tanning methods in the early 1870s. Rather than using plant-derived tannins or minerals such as alum to tan a hide over the course of weeks or months, tanners found that chromium salts could work in a matter of hours. This faster, cheaper process made the hunting of bison for hides extremely lucrative. The
slaughter that had begun in the 1850s became a massacre of unprecedented dimensions.

Calculating the scale of the butchery is considerably easier than determining the size of the original population. From various records, we know that at least 31 million bison were killed between 1868 and 1881. In 1872, 2 million bison were killed just for their hides. Take for example, Dodge City, a fledgling community that tried to call itself Buffalo City, only to be rebuffed by the postmaster general in Washington, who decided that confusion would reign given that Kansas already had towns named Buffalo and Buffalo Station. Despite the potential mix-ups in the postal service, the rejected name would have been far more apropos for a hamlet that shipped more than 40,000 hides along with seven hundred tons of bison meat in its first three months.

Professional hunters also kept careful tallies to boost their egos and ensure their fair payment. Consider Orlando A. Bond, whose records indicated that he once killed 300 bison in a single day and racked up 5,855 in a two-month period. He was presumably well compensated for his work, although no amount of money could buy back what he lost in the process. After firing tens of thousands of rounds, Mr. Bond was permanently deafened by the sound of his own rifle.

Economic profits often come at an aesthetic cost. The commander of Fort Dodge lamented, “Where there were myriads of buffalo the year before, there were now myriads of carcasses. The air was foul with a sickening stench, and the vast plain, which only a short twelve-month before teemed with animal life, was a dead, solitary, putrid desert.” But for the savvy entrepreneur, even a corpse-strewn landscape was a source of income. The killing grounds were gleaned by “bone collectors” after the slaughters, and their grisly booty was sold for eight dollars a ton for conversion into fertilizer, fine bone china, and a refining agent used in processing sugar. On the hoof, bison were not worth counting, but as skin and bone they were commodities that represented profits—and thus generated reliable records.

The frenzied massacre had political benefits for a region in which settlers were in fierce conflict with the indigenous people. Although some Indians joined in the commercial slaughter to supply the buffalo-robe trade, more saw their cultures collapsing along with the bison.
Many of the native tribes heavily depended on bison to feed their bodies and spirits. The bison were vital to the physical well-being of the Indians in the form of food and shelter, but they were also a source of social and religious inspiration. In the words of Old Lady Horse, “Everything the Kiowas had came from buffalo. Their tipis were made of buffalo hides, so were their clothes and moccasins. They ate buffalo meat. Their containers were made of hide, or of bladders or stomachs. . . . Most of all the buffalo was part of the Kiowa religion. . . . The buffalo were the life of the Kiowas.”

This dependence of native people on these creatures was not lost on those attempting to solve the “Indian problem.” General Sheridan praised the bison hunters, noting, “These men have done in the last two years, and will do in the next year, more to settle the vexed Indian question than the entire regular army has done in the last thirty years.” Although the extermination of bison as a strategy for suppressing the Indians was never explicitly stated as an objective of the government, there can be no doubt that this aspect of the industry was well understood and heartily endorsed.

In less than a century, the bison population in North America had been reduced to just 0.2 percent of its original size. By 1889, there were fewer than a thousand of these creatures left on the continent. The effects were far-reaching. With the bison no longer selectively grazing the grasses of the prairies, broad-leaved plants lost their competitive edge. Those grass species that had evolved to flourish under the erratic but intense grazing pressure of bison were also at a disadvantage. And rather than nutrients being rapidly passed through the process of a herd’s feeding and defecation (the dung being ground into the soil by the action of millions of hooves), the cycles of carbon and nitrogen became much more diffuse. Trees invaded the prairie margins as bison no longer rubbed them to death as scratching posts. The bison wallows filled in like so many neglected ponds. In a myriad of subtle but pervasive ways, the ecology of the prairie was changed forever.