Locust
Like other members of this family, locusts have antennae shorter than their bodies, song-producing organs on the forewings and hind legs, and hind legs well developed for jumping. Locusts lay their eggs in the ground; when the nymphs hatch they are wingless and move across the land by walking. Typical locusts have two distinct adult forms, a short-winged migratory form and a long-winged non-migratory form. By rubbing legs and wings against their body, locusts make a humming sound. They can hear this hum and a range of other sounds through ears on their abdomens. Adults grow to 7 cm (3 in) long, eating the equivalent of their own weight in a day. They are larger than grasshoppers and have transparent wings. They can fly for 15 hours at a time. When a lot of locusts come together, they change colour and form a swarm that can be miles wide, blotting out the sun and devouring every plant in its path. The largest known swarm covered 1,036 sq km (400 sq mi) and was made up of 40 billion insects. A locust migration is an occasional event, which follows an enormous build-up of their population. The young locusts, called nymphs, only develop into the migratory form under certain environmental conditions, which also lead to a population increase. Not all of the environmental factors involved are known, but one is hot weather. The first generation produced after a migration is not usually migratory. When migration occurs the swarms are so dense as to blacken the sky over an area of many miles. When the insects finally settle, after traveling hundreds or thousands of miles, they begin to feed, consuming enormous quantities of vegetation. They are serious agricultural pests. Spraying with solutions of arsenic and overturning the soil can destroy the eggs. They are most common in Africa and Asia, but also occur in the United States. The Rocky Mountain locust species that is now apparently extinct destroyed millions of dollars’ worth of crops on the Great Plains between 1874 and 1877. A single swarm contained an estimated 124 billion insects. Cicadas are sometimes called locusts in the United States but are related to aphids and leafhoppers, not the grasshopper.