At least one species, or kind, of locust exists on each of the major continents of the Earth. All locust species belong to the scientific family Acrididae. The insects known as cicadas are sometimes called locusts, but they belong to a different family. Like locusts, cicadas also swarm together and can destroy crops. Cicadas are known for the loud, shrill song made by males. The best-known species spends 17 years underground before emerging for five weeks of lively activity and then dying.

Locusts are about 2 inches (5 centimeters) in length. They have short and thick antennae. Their strong, long hind legs make them good jumpers. Locusts make noise by rubbing their hind legs on their wings.

Scientists believe that locusts pass through two different phases during their lives. They are usually sluggish creatures that stay away from others and blend in with their surroundings. Sometimes, however, conditions such as lack of food or too many females laying their eggs close together cause some locusts to look and act differently. These locusts gather in groups and appear restless.

Small groups of these jittery locusts may join together to form a swarm. A swarm of locusts is an amazing sight. Some people describe it as a black storm. A swarm flying across the Red Sea in 1889 was estimated to cover an area of 2,000 square miles (5,200 square kilometers). The pests can fly for days or weeks over thousands of miles. Along the way they live off the fat stored in their bodies. When they finally decide to stop, though, each locust may eat more than its body weight in food. This can wipe out entire areas of plant life in a very short time.

For many centuries prayer was looked at as the best way to stop a swarm. Today various chemicals are used to kill locusts. Once a swarm has developed, however, it is almost impossible to stop or control.