Locusts are a type of grasshopper, so the two insects share many characteristics. They both have large compound eyes, antennae, mouths with strong mandibles and elongated hind legs for jumping. Scientifically, there is no taxonomical difference between the two insects; the main difference lies in the way in which they behave.
While grasshoppers typically live a solitary lifestyle, locusts can change their behavior. The specific type of grasshopper known as a locust has the unique ability to switch from their solitary lifestyle to one that scientists refer to as gregarious. As long as conditions are favorable and they are able to find enough food, locusts are perfectly content being alone. During times when food is plentiful, locusts actually have an aversion to being in contact with other locusts. Once their food source becomes competitive, however, locusts are forced to being in close contact with each other. The overcrowding causes a release in serotonin, which initiates a chain reaction drastically altering the way they behave.
The release of serotonin causes the locusts to change colors and develop stronger muscles that can endure prolonged flight. The locusts also begin to eat more, breed quicker and easier, and actively seek the company of other locusts. Much more mobile than before, the locusts go through these changes with a very short time, usually within a few hours. The result is a swarm of locusts with the potential to travel far and destroy crops and vegetation.
When swarming, locusts are very powerful flyers with the potential to travel great distances at high speeds. If they fly at night, locusts can fly 310 miles with the help of the wind. In 1954, a swarm of locusts flew from northwest Africa to Great Britain. Three decades later, in 1988, a swarm flew from West Africa to the Caribbean. This swarm traveled 5,000 km in only 10 days.
Their ability to travel and fly is certainly impressive, but their ability to destroy crops and vegetation can be life-threatening. Locusts eat the equivalent of their own weight in a day, so when a swarm lands, that swarm has the potential to wipe out all vegetation. For farmers, this can be disastrous, and it has in US history. During the late 19th century, swarms of the Mountain locust caused $200 million in crop damage throughout several Midwestern states.
Besides their difference in behavior, there are a few other minor differences between grasshoppers and locusts. Due to the change in color when the serotonin is released, grasshoppers and locusts vary in color. While grasshoppers are green, solitary locusts are brown, adult swarming locusts are yellow and immature swarming locusts are pink. While locusts are able to fly, grasshoppers can only hop. Another difference is that grasshoppers typically eat grass while locusts eat crops and other vegetation.
Despite their differences, grasshoppers and locusts are cousins. The locusts’ ability to change their behavior and become gregarious is what makes a locust and locust. The other differences between the two insects are a result, either direct or indirect, of its change in behavior. Because of this change, locusts are fascinating insects that researchers are still learning about.