A full-grown locust averages 1.5 inches in length. And yet, in 1875, a single swarm of these tiny creatures filled 198,000 square miles—a mass encompassing "the combined areas of Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, and Vermont." So much for immensity. And here's the mystery: That same locust, 30 years later, was gone. It disappeared. Subsequent research has concluded it is extinct. In only three decades, a population of locusts larger than 3.5 trillion had been wiped from the face of the earth. Where did they go?

A game of numbers only begins to explain the fascinating story told by Jeffrey Lockwood in his book, Locust: The Devastating Rise and Mysterious Disappearance of the Insect that Shaped the American Frontier. At first glance, the book appears intended for "sciency" folk—those interested in the natural world, environmental conditions, biomes, and the like. But the subtitle says more. Indeed, the book is at least as much about the shaping of the American frontier as it is about locust biology. Certainly Lockwood knows his science: A trained entomologist and professor of Natural Sciences at the University of Wyoming, he is careful to get the research right. Yet the genius of Lockwood's Locust is not the science; it is the ability to translate that science (a nearly religious entomology) to a world that sees insects as little more than pests.

In order to do so, Lockwood must first state the claim. Using an array of staggering numbers, he proves that—in contrast to the cicadas whose swarms are making news this summer—locusts were far more than merely annoying to the early settlers of the West. In many locales, locusts could mean starvation. ...