What it is
The Rocky Mountain locust (Melanoplus spretus) was a grasshopper of western North America that formed some of the largest insect swarms ever recorded. The International Union for Conservation of Nature lists it as Extinct.
Range
River valleys of the Rocky Mountains, from where swarms spread across the Great Plains of the United States and Canada.
What happened
Between 1873 and 1877 its swarms ate crops across the Great Plains. The insects bred in a few sheltered river valleys, and when settlers ploughed, watered and grazed those valleys, the eggs in the soil were destroyed.
When / status
Last specimen collected in 1904.
Human role
Ploughing, irrigation and trampling by livestock in its breeding valleys destroyed its eggs.