Locusts on the Plains

Is it easy to recognize historical reality versus that charming “tall tale” exaggeration that was (and still is) so common? “Streets of gold”, for example, were certainly exaggeration. Other exaggerations can be nearly as obvious. Some cases, though, can require research and careful thought to determine if they can be taken at face value or to what degree toning down is required. Of course, often the exaggeration itself is interesting and says something about the personality of the source. Sometimes though, the surprise is that a tale that seemed so obviously to be exaggerated turns out to be true or even an understatement.

One night while reading On the Banks of Plum Creek (the third of the “Little House” books by Laura Ingalls Wilder) for my daughters, I read these lines-

A cloud was over the sun. It was not like any cloud they had ever seen before. It was a cloud of something like snowflakes, and thin and glittering. Light shone through each flickering particle.

There was no wind. The grasses were still and the hot air did not stir, but the edge of the cloud came across the sky faster than the wind. The hair stood up on Jack’s neck. All at once he made a frightful sound up at that cloud, a growl and a whine.

Plunk! Something hit Laura’s head and fell to the ground. She looked down and saw the largest grasshopper she had ever seen…

The Cloud was hailing grasshoppers. The cloud was grasshoppers. Their bodies hid the sun and made darkness. Their thin, large wings gleamed and glittered. The rasping whirring of their wings filled the whole air and they hit the ground and the house with the noise of a hailstorm.

Exaggeration? A swarm large enough to perform the proverbial trick of blotting out the sun would seem to be unlikely. Why do we never hear of anything even approaching such a phenomenon blighting the plains today? The truth turns out to be stranger than I imagined.

The villain in this and many a settler’s story was the Rocky Mountain Locust. The difference between a grasshopper and a locust is, in a sense, minimal. Locusts are not members of separate species. All insects go through several distinct phases as they advance through their life cycles from egg to adult and many are accomplished shape-changers. Who would identify a caterpillar as a butterfly-to-be if they did not already know it to be true? Some grasshopper species, though, add an extra twist to the concept of the life cycle- they add a cycle that spans not the phases of an individual life but the generations of a population. If environmental conditions permit their numbers to rise or force them into islands of green in times of drought and their population becomes denser, the grasshoppers go though hormonal changes. The female grasshoppers pass the influence of these changes on to their eggs which hatch into a world that may be even more crowded than that of their parents, amplifying hormonal changes further and a new outbreak of locusts is born. One species with two very different sets of behaviors and body types so different that they were thought by scientists to be obviously separate, though distantly related, species.

Grasshoppers are loners. Locusts love company. Grasshoppers have short wings. Locust wings are long. The grasshopper of a species might be green and the locust form brown. Grasshoppers may do damage but their name implies they are most famous for hopping through the grass. The name locust comes from the Latin phrase “locus ustus” meaning a place destroyed by fire, which captures the essence of a landscape after locusts depart. These two creatures are so obviously different and yet during experiments and observations of wild populations a century ago, innocent grasshoppers lived in conditions that forced them to to jostle each other at close quarters. Many eggs hatched either into a seemingly new form, both grasshopper and locust-like, or into outright locusts. Reduced population density led to grasshoppers growing up from the eggs of locusts. For the most part though, you need not fear that your backyard’s collection of grasshoppers will bring forth an army of locusts. Most species of grasshoppers remain grasshoppers no matter what. They are Dr. Jekylls without a Mr. Hyde lurking within.

There is at least one more major difference between grasshoppers and locusts. Grasshoppers tend to stay put. Locusts are migratory and on the American plains they ran into another great migratory species- the American homesteader.

Many an ancestor who went west, we are surprised to find later in the East, if we even think to look there. The Rocky Mountain locust was one of the reasons that people abandoned their new lives on the plains. Without being the least bit conscious of a war of migrants, the locust won many battles. As early as 1827, Swiss settlers deserted the Red River Settlement in Canada, at least in part, due to “grasshoppers.” Even earlier, William Clark recorded that while returning from the Pacific Ocean in 1806 he observed

that the emence Sworms of Grass hoppers have distroyed every Sprig of Grass for maney miles on this Side of the river, and appear to be progressing upwards.

Jeffery Lockwood wrote the amazing biography of the Rocky Mountain Locust in his book Locust. A book I couldn’t put down despite having little entomological interest myself. To understand how truly amazing the story is one needs to understand how far beyond Laura Ingalls Wilder’s account the truth actually lies. You could get the idea that if true at all, what she saw was a freak local occurrence. A few farms over everything must have seemed normal, one might believe. Later on, it is clear that the whole area was devastated but the Rocky Mountain Locust went far beyond that. It was no exaggeration. One Minnesota farmer recorded that after finding every spot of ground he checked crammed full of egg pods, he sat down and counted out 150 eggs per square inch. He then extrapolated that to an astounding 940,896,000 eggs buried in every acre of his land. You might be tempted to discount that as either wildly off or a special case perhaps only locally valid; yet Lockwood found another measurement and instead of contradicting the first, this measurement confirmed it. Twenty years before that Minnesota farmer was dumbstruck, two men in Utah made measurement after measurement and arrived at 118.519 eggs per square inch. That gives 743,424,000 eggs per acre in a different place and at a different time.

Nearly a billion eggs per acre led to quite a spectacle when they began to hatch. People reported the earth seeming to boil as the nymphs rose to the surface. Clearly, far from all of these eggs hatched but enough did. An unbelievable number did. The prime example, the swarm of the 1870’s, was the greatest ever recorded. By telegraphing back and forth across the plains Dr. Albert Child calculated the size of what he saw passing over his head in Nebraska- one swarm that by his reckoning covered 198,000 square MILES. Lockwood points out that this is the equivalent of covering every state of the eastern United States from Maryland and Delaware in the south to Maine in the north and he could have thrown in half of West Virginia and still not quite gotten up to the size of the swarm. If you prefer more southerly climes, this swarm could have covered California and had enough locusts left to more than cover South Carolina. No other species is known to even remotely approaches this. The largest locust swarm outside North America occurred in Kenya in 1954. It was less than 100 square miles. No other animal species ever reaches these numbers for a single concentration.

Of course the swarm had a volume, not just an area. Child got out his telescope and tried to get a feel for how thick the cloud of insects above him was. His result? One quarter to one half a mile thick and he confessed that he might be underestimating. The swarm could have been a mile thick. Estimates of the number of individual locusts involved vary but all are awe inspiring. Lockwood estimates three and one half TRILLION insects, that’s 3,500,000,000,000. Others disagree but as with almost everything else about this insect they claim the already incredible is, in fact, on the low side and place the number nearly four times higher, at 12,500,000,000,000 or twelve and a half trillion weighing in at 27.5 million tons and all on the wing overhead stretching farther than you could see. Imagine if you can what that would look like flying overhead. Nothing else would have been visible from horizon to horizon and, as Laura Ingalls Wilder and many other recorded, not even the sun would be visible. Then there was the sound. First the awful buzzing, rasping, humming drone that came from everywhere and then, if you were unfortunate enough to experience their decent, the sound of a nearly infinite number of tiny jaws eating. Witnesses described it as the sound of a vast wind blown fire crackling everything to destruction.

The locusts didn’t just eat wheat crops and tree leaves. Such vast numbers needed every source of sustenance to avoid starvation. They ate dead animals. They ate their own dead in desperate cannibalistic feeding frenzies- so killing them only fed them. They ate fence posts and the paint from houses, even the siding itself. In need not just of calories but of minerals, they ate not just the product of the farmer’s labor but the outer layers from tool handles to get even the salt that his sweat had left behind. They ate the wool off the backs of live sheep and the clothes from people who left their homes. One report even had them tasting the flesh of a live soldier who collapsed from exhaustion. Imagine the horror people must have felt when they first encountered such a phenomenon- beyond any Biblical plague visited upon Egypt. What had they done to deserve the wrath of God?

The last and strangest twist gets back to the question I had when I read for my daughters. If this is true, why don’t we read about the Rocky Mountain locust in the news today? Why aren’t we occasionally treated to CNN reports of half of Kansas being swallowed whole? The answer is that less than three decades after numbering in the trillions, the Rocky Mountain locust population had fallen and fallen hard, to zero in fact. No live locusts have been seen since 1902. As far as anyone knows the Rocky Mountain locust is extinct and much of Lockwood’s book is dedicated to finding the culprit in this spectacular whodunit.