Locusts are more than just a biblical tale—though they do have the ability to be a very destructive insect, wreaking havoc on plants and crops. Some people may think that the terms locust and grasshopper can be used interchangeably. Locusts and grasshoppers are similar and share certain characteristics—but there is one main difference between the two. Keep reading to learn more.

grass and leaves

So, what is the difference between a locust and a grasshopper?

Locusts are actually a species of grasshopper. And that means that all locusts are grasshoppers, but not all grasshoppers are locusts—in fact, less than 20 species worldwide have locust characteristics. Locusts are considered part of the short-horned family of grasshopper. Within the short-horned family are three subfamilies: the spur-throated grasshoppers, the slant-faced grasshoppers, and the band-winged grasshoppers. The Rocky Mountain locust, which is detailed more in a later section, is a highly destructive locust considered part of the spur-throated subfamily.

Locusts are distinguished by shared behavioral characteristics, rather than physical characteristics. Locust appearance can vary from species to species. The most famous behavior, and the biggest difference between locusts and grasshoppers: Locusts have the ability to swarm.

Locusts and their swarms

How and why locusts swarm

Perhaps the most distinct characteristic of a locust is its ability to swarm. Other grasshoppers do not have this ability and instead live solitary lives. Locusts can also live solitary lives—but other times, like in desert locusts, they enter a gregarious behavioral state. And this is when they swarm. Solitary and gregarious locusts even vary in appearance: It is during a swarm that they will develop larger, stronger muscles and bright vibrant colors. When they are not swarming, they are often smaller in size and duller in color.

Research has shown that changes in brain chemistry influence swarming behavior in desert locusts. According to this new research, an increase in serotonin is the primary cause for changing behaviors and the eventual change into the gregarious, swarming phase. This happens when many locusts come in close contact with one another. Locusts that swarm generally live in dry, barren regions without much rain. During dry periods, locusts are forced into the smaller areas that still have food—causing crowding and eventual swarming.

When locusts swarm, they can be devastating by causing serious damage to agriculture and crops. One kind of locust, the desert locust, can at times affect approximately 20% of the world’s land surface. They’re found in Africa, the Middle East, and Asia. The desert locust causes damage in Africa, in areas that rely on sustenance farming. One swarm can have around 80 million locusts, with a swarm of this size being able to eat over 400 million pounds of plants in a single day. Locust swarms are also able to travel great distances. One swarm in the 1950s flew all the way from northwest Africa to Great Britain.

Locusts in the United States

While there isn’t as much activity now, in the 1800s, the United States was no stranger to swarming locusts. In 1874, a famous swarm of Rocky Mountain locusts invaded the Great Plains. In fact, the swarm was estimated to be twice the square mileage of the state of Colorado. Unlike locust swarms of today that only number into the millions, this swarm supposedly had trillions of locusts. And then after the swarm was over, the Rocky Mountain locusts have not been seen again, and are thought to be extinct. In the 1930s, a different locust species swarmed: the High Plains locust—but did not cause nearly the devastation of the 1874 swarm.