An enigma that once numbered in the trillions, the Rocky Mountain Locust is a mystery of the New World that has baffled scientists and frustrated immigrants since it’s discovery by colonists. Though once dined on by many native populations of North America, they became a nuisance on the bumper crops planted by immigrants heading westward past the Rocky Mountains in which their name stems.

Their natural range was in the upper river basins of the Northern Rockies, where they bred in hot and dry sands. They thrived on the concentrated sugars that exist in the stalks of prairie foliage. This diet made it easy for them to sweep westward, using the jet stream as a current to their travels. Despite this, their damages were reported as far east as Maine in the mid 1700s and would continue into the 1800s.

The last of their major swarms in the late 1800s caused $200 million in crop damage throughout Colorado, Minnesota, Nebraska, and other states. Their swam grew so bad, that one sighting in 1875 estimated that one swarm was 198,000 square miles (510,000 km2) large and weighed in at 27.5 million tons. Farmers began to take action, switching to winter wheat which dissuaded consumption and putting bounties on the eggs of the locust. Plowing and irrigation systems destroyed the life cycles of this insect and soon they were dwindled so much in number that the last known sighting was in 1902.

Despite this, there was much argument well into the new century of if the locust was still alive. Some argued with convincing observations that it could have gone into a solitary phase of the grasshopper stage, or perhaps went dormant in its range. Analysis of specimens from both collections and those found in the “Grasshopper Glacier” of Yellowstone Park found, however, that the Rocky Mountain Locust was indeed a distinct species of its time and was now gone forever, leaving North America the only continent besides the Antarctic to not have a native locust species.

Extinction Date According to the IUCN Red List: 2014