In 1876, the U.S. Congress declared the locust “the single greatest impediment to the settlement of the country between Mississippi and the Rocky Mountains.” Throughout the nineteenth century, swarms of locusts regularly swept across the American continent, turning noon into dusk, devastating farm communities, and bringing trains to a halt. The outbreaks subsided in the 1890s, and then, suddenly—and mysteriously—the Rocky Mountain locust vanished. A century later, entomologist Jeffrey Lockwood vowed to discover why.Locust is the story of how one insect shaped the history of the western United States. A compelling personal narrative drawing on historical accounts and modern science, this beautifully written book brings to life the cultural, economic, and political forces at work in America in the late nineteenth century, even as it solves one of the greatest extinction mysteries of our time.