Extremely abundant up until the end of the 1800s, the Rocky Mountain grasshopper, or Rocky Mountain locust (Melanoplus spretus) went extinct extremely suddenly, within 25 years of an enormous plague in 1874. They are thought to have been driven to extinction by farmers digging up their eggs and converting breeding habitats to croplands. This destructive migratory locust pest cost hundreds of millions of dollars in damaged crops (grain crops, primarily) in the 1870s, across its range through the dry, high elevation prairie states on the eastern slopes of the Rocky mountains, up into British Columbia, and down as far as Colorado. It has an entry in the Guinness book of world records for “greatest concentration of animals”, with swarms exceeding 10 trillion insects. Although their rapid demise meant that few specimens were kept before extinction, many millions of locust bodies are preserved in the glaciers of the Rockies.

(Wikipedia 2011; Garcia 2000)