How Rocky Mountain Locusts And Mountain Glaciers Tell A Story

Oct 2, 2020

On a frosty early August morning, Jordan Harrison and Corey Anco packed for a day of off-trail hiking in the Beartooth Mountains. Anco is the Draper Natural History Museum assistant curator and Harrison is a field biologist for WEST, Inc.

"We are leaving base camp here at Little Goose Lake and we are going to head up to Grasshopper Glacier," said Anco. They're off in search of a glacier that hasn't been measured in over 40 years.

For about two miles, the two researchers followed a trail through an alpine meadow towards a hill of rocks and up to a saddle—on the other side of which, should be Grasshopper Glacier.

When its size was documented decades before, by one researcher, it was estimated to be about five miles long.

As Anco and Harrison reached the top of the saddle, Harrison stopped and said, "There it is!" Ahead is a sheet of snow spread along the other side of the saddle.

"Right below us you can see a light discoloration of the rocks where the snow and ice that was above the glacier from the winter has melted off," said Harrison. "And looking further down the slope you can imagine how this glacier used to extend out five miles."

But it's not one consistent chunk. Harrison estimated it's about a mile. The researchers descended down to the middle of the sheet of ice. Harrison stopped as he noticed little black specks on the snow.

"There's a living grasshopper on the glacier right now. And they're really cold, so they're not moving," he said. "And you can imagine just a visualization here of modern grasshoppers coming down landing on this glacier. And if we've got a snowstorm overnight, they might very well have been entombed as well."

Anco and Harrison look over a map standing on Grasshopper Glacier

When Grasshopper Glacier was first documented, in the early 1800s thousands of frozen Rocky Mountain Locusts deposits were found. But Anco said as the glacier has been receding, these deposits have disappeared.

"The rumor is that many of the, if not all these extinct locusts, the Rocky Mountain Locust have washed out of the Grasshopper Glacier already," said Anco.

And this is why Anco and Harrison are here. They want to document both the glacier and possibly the Rocky Mountain Locust who at one point, with the right conditions, swarmed the west in the trillions.

UW professor and grasshopper expert Jeff Lockwood said before Europeans arrived, the Rocky Mountain Locust was a food source, but white settlers didn't enjoy them as much.

"They were absolutely devastating to the crops," said Lockwood. "A swarm of locusts could reduce a farmer's field to basically bare dirt in a few hours," meaning starvation for the settlers.

As the swarms moved through mountain valleys, Lockwood said the wind would change and some would be deposited.

"So, you can imagine them getting deposited on the ice, and then relatively quickly, because their bodies are dark they're going to sort of melt into the snow cover," he said. "and they're going to be immobilized. They're cold blooded, so they're stuck, and they're going to die, they're going to freeze.

The issue was so dire that the federal government got involved in solving the locust swarm problem but then all of the sudden the swarms stopped on their own. That was in the beginning of the 20th century and nobody knew why. Lockwood said it turned out that fertile river valleys were being converted into agriculture fields ridding the habitat of the Rocky Mountain Locust egg beds.

"If you cut enough of the strands of the net, eventually it falls apart. And we think that's what happened to the Rocky Mountain Locusts as a bunch of unwitting farmers armed with cows and plows wiped out the greatest threat to agriculture in the western United States without knowing what they were doing," said Lockwood.

Back at Grasshopper Glacier, Harrison leaned down, his nose almost touching the ice and carefully shoveled out what looked like a black speck. He poured water over it.

"Definitely not recent," said Harrison under his breath.

Anco looked closely at the speck in Harrison's hand, "Yeah, man, it looks like you can see a leg here."

"Yeah, it might be part of one."

It doesn't look like much, just a short little stick of mush, but there's more to it than that.

"What we're looking at here is, it appears to be like an invertebrate that looks severely flattened, and at an advanced stage of decay," described Anco. "But there are some somewhat identifiable characteristics, like one piece looks kind of like a leg, a segment of a leg."

They continued looking around but didn't find any full, intact specimens. For Anco and Harrison, the trip was still a success. To them these glaciers tell a story that they want to share.

"It's a story that not only tells the history of the biology and the ecology of the area, but also what that impact was to human life at this time," said Anco. "And that helps to connect us a little bit more to this landscape."

And they will continue searching throughout the Beartooth Mountain glaciers for a Rocky Mountain Locust specimen while also documenting the glaciers themselves.

Have a question about this story? Contact the reporter, Kamila Kudelska, at kkudelsk@uwyo.edu.