This insect caused millions of dollars in damage right around when the passenger pigeon was at its peak, but then suddenly disappeared never to plague the western US again. The plague in 1874 holds the Guinness Book of World Records title for the greatest concentration of animals ever speculatively guessed- nearly 12.5 trillion grasshoppers! But in only 28 years they would go from blacking out the sun to completely extinct.
Locust: The Devastating Rise and Mysterious Disappearance of the Insect that Shaped the American Frontier by Jeffery A. Lockwood
Episode 431 of The Dollop: Year of the Locust