Locust is the name given to the swarming phase of short-horned grasshoppers of the family Acrididae. Locusts are grasshoppers that are capable of swarming (see below) under certain conditions. The origins and apparent extinction of certain species of locust- some of which reach 6 inches (15 cm) in length- are unclear.

These species can breed rapidly under suitable conditions and subsequently become gregarious and migratory. They form bands as nymphs and swarms as adults both of which travel great distances during which they can strip fields rapidly and in so doing greatly damage crop yields. An exacerbating factor in the damage to crops caused by locusts is their ability to adapt to eating almost any food plant.

Some examples of Locust species are: the Migratory locust (Locusta migratoria), Red locust (Nomadracis septemfasciata) and the Desert locust (Schistocerca gregaria). The latter is probably the most important in terms of its very wide distribution (North Africa, Middle East and Indian Subcontinent) and its ability to migrate very widely.


According to Judaeo-Christian tradition, a swarm of locusts comprised the eighth plague in the Biblical story of the plagues of Egypt.


Various tree species of the genii Gleditsia and Robinia are commonly referred to as locust trees, including:

The fruit of the carob tree (Ceratonia siliqua) is also known as locust bean.


Locust is also the name of a pioneering SMS chat community in the UK.