The extinct were-beasts of the American midwest

We may earn a commission from links on this page.

And people say were-animals don't exist! One particular were-beast nearly wiped out the pioneers before anyone realized that it even had two different forms — or what, exactly, made its harmless version transform into something far more deadly.

If you’ve ever read the Little House series, you’ve seen the most famous literary appearance of the Rocky Mountain locust. As the family is happily tending their prosperous farm, they see a strange, glittering cloud moving towards them. The cloud settles overhead, and starts raining locusts. They frantically set fire to everything they can in order to drive the insects off with the smoke, but nothing works. The prairie grasses first break under the weight of the locusts, then are eaten. Every tree and bush is stripped bare. Nothing’s left.

This was the story all over the country. Locusts ate their way through 125,000 square miles of the midwest. They weren’t deterred by fire or poison. When farmers put up barriers, they ate through them. They could not be stopped. Eventually ,they disappeared and people started planting. Then the eggs they'd laid in the soil hatched, and it happened all over again again.


Since these things didn’t happen every year, it was reasonable for people to ask where exactly this onslaught came from. Where were these hordes of insects hiding out? And why didn’t people see even a single locust when the animals weren’t swarming? The question wasn’t answered until 1921, when an entomologist called Boris Uvarov linked locusts to what was considered at the time to be an entirely different species of insect.

Uvarov noticed something about certain species of grasshoppers. While most had consistent behavior, about a tenth of 1% of the 10,000 known types of grasshoppers had characteristics that seemed to be similar to certain types of locusts. Uvarov put these similarities together and came up with something called phase theory. These approximately 12 species of grasshoppers had three phases: a solitary, a transitional, and a gregarious phase. Solitary grasshoppers are just that; they’re on their own, they stick mainly to the grass with stubby little wings to help them fly a bit, and are tinted green to light brown to blend in with their habitat.


When environmental stresses push them together to compete for resources, they can enter into a transitional phase. They turn a little darker. They get a bit more social. The female grasshoppers lay eggs that bring on the final phase.


Gregarious phase grasshoppers are no longer grasshoppers – they’re locusts. It’s not surprising that they were taken for a separate species for so long. The proportions of their body and head are completely different, and they have long wings which help them fly. They’re also no longer concerned with blending in. Locusts are dark, although they sometimes get flashy bright orange accent marks.

Their new behavioral defense is sticking together. When the swarms hatch, they are so numerous that they can’t be defeated. Farmers who set their animals on the swarms, hoping to at least eat and sell the meat, watched as animals ate themselves to death. A diet of certain locusts is toxic, and poisons the meat, making even dead animals useless. The swarms were vegetarian, and no one was bitten by a locust, but they were fearless, relentless, and utterly unified – completely unlike the ordinary grasshoppers. They’d physically and behaviorally become different animals.


When Uvarov first discovered that two separate animals were actually one, people began tearing through information on what exactly changed them. At first, they thought it was a sole result of the color transition, but this was disproved. Today it looks like simply being around too many other grasshoppers starts the transition. Gregarious phase locusts pass chemical signals to each other, but also require both visual and tactile stimulation. Once the population reaches a certain density in a certain area, the change begins.

Uvarov proved the transition between the seemingly distinct species, but his goal wasn’t just scientific discovery. He wanted to end the swarms and their crippling effect on agriculture. His first suggestion was a change in tactics. People were accustomed to battling the huge swarms of locusts; Uvarov showed that, like any true were-animal, a locust was most vulnerable in its gentler shape. Keeping grasshopper populations low enough to keep from bringing on the change was more effective than trying to fight tens of millions of flying enemies. Swarms, in one record-breaking case, got to be the size of California. They couldn't be killed.


This was the strategy that was, unknowingly, used on the Rocky Mountain locust. In the end, farmers proved more effective killers than the locusts, and they managed it accidentally. As farming spread across the country, the upheaval of plowing the soil killed off the grasshopper’s eggs. The last Rocky Mountain locust was spotted in Canada in 1902. The extinction of any species is a loss, and should be prevented, but this one did have some benefits. We no longer have to worry about state-size swarms of bugs... except in literature.

Via Wiley Online Library, Encyclopedia of Entymology, Deserts, and Wicked Bugs.

Top Image: National Archives