Locust (29 page)

Riegert proposed, “The breaking up of the sod and the overgrazing that followed hard on the heels of the bison migrations changed the grassland habitat for many species of grasshoppers.” There is no doubt that the herds churned the soil into a pulverized mixture of manure, dust, and roots. Riegert asserted that members of the genus
Melanoplus
found the disturbed soil to their liking, and perhaps this was true in some species. We often find
M. bivittatus
, the two-striped grasshopper, laying its eggs along roadsides and crop borders where the soil is pulverized. However, there was no evidence that
spretus
favored such soil conditions. Indeed, Riley’s work strongly suggested that the locusts preferred to lay their eggs in compact, rather than loose, soils. The locust generally avoided laying eggs in newly plowed land. It seems that the locusts were entirely capable of producing viable pods of eggs in habitats that would not have been transformed by bison.

Riegert also proposed that overgrazing favored the locust. He contended that the locally intensive grazing of bison, especially in drought years, would have created conditions conducive to the breeding of locusts. Although it is true that
spretus
laid eggs in heavily grazed pastures, grassy and weedy fields also were quite acceptable. Indeed, almost any dry, reasonably compact, sandy site would do in the midst of an outbreak. The only habitats that appeared to be consistently rejected were those with rank vegetation in saturated conditions. Both overly loose or heavily compacted soils were often avoided as well. Moreover, the hatching locusts needed food—which is why Riley advocated burning the prairies in the spring to starve out the nymphs. So, an immense swath of overgrazed land in the midst of a drought would hardly have offered the ideal conditions to foster a buildup of locust populations. Perhaps as a last gasp for this aspect of
the theory, Riegert even suggested that the locust nymphs might have made use of bison dung for food, presumably allowing the insects to dine in recently denuded grasslands. Although
spretus
was observed to feed on dung, this was surely a minor and suboptimal food source. After all, Riley reported that hungry locusts would also consume dead mammals and sheep’s wool, both of which were abundantly available in the years of the bison’s decline, when the range was stocked with domestic animals.

 

Nobody exploits a good logical fallacy as well as the advertising industry, and the most egregious snake-oil salesmen almost invariably evoke
post hoc, ergo propter hoc
, which translates as “after this, therefore because of this.” On television, a woman applies a bit of Carnal perfume in the opening scene, and the next moment we see men drooling as she flits by. In magazines, the first picture has the bald guy’s head, the next one has a bottle of Scalp Fertilizer, and the final one shows the fellow with Sampsonesque locks (and sometimes with entirely different features, although we’re supposed to believe that the tonic grows hair rather than altering eye color or the shape of one’s nose). To avoid litigation, the clever advertiser never actually states that the perfume elicits lust or the tonic produces hair—these leaps of illogic are left to the viewer. But we are enchanted by the power of cause and effect, and so we presume that sequential events are causally related. The decrease of the bison right before the decline of the locusts was just too neat and obvious for the former not to be the cause of the latter. But Riegert’s ecological linkages were weak, and it seemed to some at the time that his version of the “bison theory” failed in the context of a final consideration.

While bison were being wiped out across the Great Plains, cattle and sheep were being shipped in. Wyoming had fewer than 10,000 cattle in 1870; just fifteen years later there were more than a million. And this trend was seen across the West. The population of livestock in the eleven western states grew from perhaps 9 million animals to more than 25 million between 1870 and 1890. So, while 30 or 40 million bison were being gunned down, millions of cattle were being bred up.

In terms of feeding and movement, cattle are not the exact ecological equivalents of bison. Cattle are much more dependent on water sources, and their herds are smaller and less mobile than bison herds. But there are some substantial overlaps in the effects that these two grazers have on the rangeland. For example, both have a strong preference for grasses and churn the soil with their hooves. And so, 20 or 30 million cattle certainly sustained many of the conditions, at least in some locales, that the locusts may have exploited.

Overstocking the range became the norm in the early 1880s. Texan and eastern cattle were added to herds already feeding on the northern plains. By the fall of 1883, about 600,000 head of cattle filled the Montana range, along with an equal number of sheep. Although the range was at its capacity, the natural increase of the herds and the importation of more animals from Texas in 1884 led to deteriorating conditions. A rancher noted, “It takes 20 acres on a new range to feed one cow, after the range has been grazed two years it will take almost 25 acres, and after six years all of 40 acres.” Overgrazing and trampling were inevitable, even if these effects were more continuous and evenly distributed than with bison.

And so, alfalfa, weather, and bison all had unimpeachable alibis. The list of suspects that had the means of victimizing the locust was dwindling fast. There was, however, one last factor with the spatial scale to end a life as sweeping and glorious as that of the Rocky Mountain locust.

Although bison stretched across the Great Plains, there was an even more ubiquitous life form with far greater effects on the environment of the Rocky Mountain locust: the American Indian. Indeed, the elimination of the bison was an ecological means to a political end—the suppression of the Indians in the western United States. The native people and native insects were viewed as serious impediments to realizing America’s destiny. Allusions to their one-two punch were exploited in the free-for-all competition for settlers in which neighboring states referred to one another as a “barren, grasshopper-ridden,
Indian-infested desert where no farmer was likely to succeed.” During the late 1800s, the population of Indians in the western states was reduced by as much as 50 percent by disease, war, and starvation. But this numerical decline does not begin to reflect the scope of the changes wrought on the native people and their land.

The establishment of the reservation system and the consequent displacement of virtually all Indians from their homelands by 1885 resulted in drastic changes across the West. With this uprooting and resettlement in strange and unfamiliar places, the people were unable to conduct their lives as they had for thousands of years. Along with the brutal and sudden suppression of the Indians themselves, their activities—hunting, gathering, fishing, planting, and harvesting—vanished from the landscape. The Native Americans were intimately dependent on a host of plants and animals for food, clothing, and shelter. Could such relationships have been reciprocal, with locusts having adapted to conditions or resources made available by the Indians? Could a strange and perverse twist of history have led to a sequence of events in which the decline of the native people somehow precipitated the extinction of the Rocky Mountain locust?

In the 1970s and ’80s, anthropologists were coming to realize that the Indians didn’t simply live in passive harmony with nature. Rather, they extensively and intentionally altered the landscape. The “noble savage” conceptualization of these people gave way to a much more sophisticated understanding of Native Americans as savvy environmental engineers. In 1982, Stephen Pyne, an ecological historian at Arizona State University, made this radical assertion: “So extensive were the cumulative effects of these [ecological] modifications that it may be said that the general consequence of the Indian occupation of the New World was to replace forested land with grassland or savannah.” Although there is still ardent debate as to the role that the earliest Americans played in the extinction of the mammoths and other giant (and presumably tasty) mammals of the Pleistocene, there is no argument concerning their role in shaping the quality and quantity of the prairies. As Pyne so effectively documented and clearly expressed, the greatest ecological change imposed by the Indians was the use of fire to vastly expand the grasslands upon which the bison—and ultimately
the people—depended. By burning the land, the Indians shifted the competitive balance in favor of grasses. Fire killed sprouting shrubs and trees, whereas the grasses quickly regrew from seeds or root crowns. And although Pyne did not make the ecological connection explicit, the entomological implications were compelling: Locusts, like bison, favored grasslands over forests.

Among Riley’s various recommendations for preventing outbreaks of the Rocky Mountain locust, he had advocated an aggressive program of tree planting. He recognized that forested areas were never used for egg laying and that heavily treed lands were barriers to the advance of the locusts. Riley even hypothesized that forests were the factor limiting the eastward spread of the locust. By his estimates, forests covered about 6 percent of the land from the Mississippi River to the Rocky Mountains and 30 percent of the land to the east of the Mississippi—a sharp change in the landscape that served as the Maginot Line for locusts.

Riley repudiated the idea that grass fires caused the droughts that triggered the locust migrations. He did, however, admit a possible connection among Indians, fires, prairies, and locusts. This conspiracy involved a far more ancient ecological association:

If Indians did sustain the ecological conditions suitable for locusts by burning back encroaching shrublands and forests, then they may have been even more clever than we suppose. Locusts are a serious problem for farmers, but they are a valuable food for hunter-gatherers. An anthropological study at Lakeside Cave at the western edge of the Great Salt Lake revealed human feces consisting mostly of grasshopper parts with a matrix of sand. The scientists witnessed
grasshoppers being blown into the lake and forming rows of up to ten thousand bodies per foot, with a light coating of sand. As such, one can easily imagine the Indians scooping up this salted, sun-dried feast. We now know that grasshoppers were a regular food for Indians in the Great Basin and on the Colorado Plateau, including the Ute and Southern Paiute. John Wesley Powell, the famed geologist-ethnologist of the late 1800s, noted that:

Compared to the danger and labor of hunting bison or other wily mammals, locusts were a fantastic bounty. These little morsels are 60 percent protein and chock-full of calories. According to anthropologists, one person could collect 200 pounds of sun-dried grasshoppers in an hour. With no processing time, this crunchy load would yield 273,000 calories, the equivalent of 500 supreme pizzas. A person gathering seeds or nuts would be lucky to provide 1,000 calories in the same time. A deer or antelope would likely net only a tenth of this energetic sustenance. As for taste, the Goshute Indians of western Utah, after first tasting shrimp, called them “sea crickets.” Riley would have been pleased.

All of this makes a wonderful ecological and ethnological circle linking Indians to fire, fire to prairies, prairies to locusts, and locusts back to Indians. But does breaking this cycle by eliminating the Indians provide a plausible basis for the extinction of the Rocky Mountain locust? Probably not. Although there is evidence of forests encroaching on grasslands after the Indians were extirpated, the scope
and rate were far less than necessary to reasonably account for the disappearance of the locust. After all, we’re talking about forests, and trees don’t invade large areas in a matter of twenty-five years. And, of course, Indians were not the only source of fire in the West. Lightning certainly sparked conflagrations on a regular basis, toasting trees and scorching shrubs. Fire-dependent plants did not disappear along with the Indians, so it seems most unlikely that the locust would have suffered an even more drastic fate than these plants. Furthermore, even in the complete absence of fire not all grasslands would convert into forests or shrublands. Precipitation and other factors limit the distribution of woody plants on the Great Plains. In the final analysis, the ecological links were simply too weak, and the case against the accused was dismissed.

 

On Sir Boris Uvarov’s last visit abroad, he returned to his native land. Uvarov attended the International Congress of Entomology in St. Petersburg in 1968, where he was welcomed as a hero and honored as a long-lost son. Although a lesser man might have been cast as a defector, Uvarov had been instrumental in helping Russian science rise to a justly deserved status by ensuring that his countrymen were well placed in the world and that their work was published in widely read journals. In his address to a packed auditorium, he maintained that the study of locusts “would make possible a gradual replacement of direct control by methods of ecological regulation of populations.” He considered insecticides “mere palliatives.” What we needed was the capacity to change ecological processes on the scale of whole landscapes, undermining the very resources that locusts needed to develop into swarms and devastate agriculture. What we needed in Asia and Africa was whatever had happened in North America to snuff out the Rocky Mountain locust.