The word "locust" may refer to any of three types of insects: the swarming phase of short-horned grasshoppers, the eastern lubber grasshopper, or the cicada. Swarming locusts can cause massive crop damage, while the other two types are sometimes garden pests.
Swarming locusts belong to the family Acrididae. Also known as short-horned grasshoppers, they are distinguished from other large grasshoppers by their tendency to form huge swarms composed of up to 80 million individual insects. Locust swarms have occurred on all the inhabited continents but have been most common and most damaging in areas of Africa where subsistence farming is practiced. Each locust can eat up to its own weight in plant material daily, threatening human populations with famine.
The eastern lubber grasshopper is also sometimes called a locust but belongs to a different family, Romaleidae. It does not form large swarms, nor does it eat as much per individual as the swarming types, but it will travel long distances to obtain its favorite foods. In gardens, it may attack young citrus trees, cruciferous vegetables, collards, lettuces, carrots, squashes and flowering plants of the Amaryllis family. These locusts can be controlled by hand-picking or mowing weeds and tall grass near gardens.
Cicadas are best known for their droning songs and for some species' periodic cycles that result in large swarms of adult insects that emerge every 13 or 17 years. Egg-laying females sometimes damage the twigs of trees in orchards, causing the tips to die, and the cicadas' nymphs can cause root damage to plants.