A locust is a type of large grasshopper that sometimes transforms into something far more destructive. Most of the time, locusts live alone and act like ordinary grasshoppers, munching on plants and staying in one area. But when conditions are just right (usually after heavy rains create lots of food), something remarkable and frightening happens: they change color, behave differently, and most importantly, they start gathering together in enormous groups called swarms.

These swarms can contain billions of locusts and stretch for miles across the sky, looking like dark, moving clouds. A single swarm can eat the same amount of food in one day as 35,000 people. When locusts descend on farmland, they devour nearly every plant in sight: crops, leaves, and even bark. Throughout history, locust plagues have caused devastating famines. The Bible describes swarms of locusts as one of the plagues of Egypt, and even today, countries in Africa and Asia sometimes face locust invasions that threaten food supplies for millions of people.

Scientists still study how locusts transform from peaceful loners into members of these destructive swarms. The word locust sometimes appears in other contexts too, like the locust tree (named because its seed pods supposedly resemble the insect) or when people describe anything that arrives in overwhelming, consuming numbers.