locust

thumb|Locusts, such as this migratory locust (Locusta migratoria), are grasshoppers in a migratory phase of their life. thumb|Millions of swarming [[Australian plague locusts on the move]]

Locusts (derived from the Latin locusta, locust or lobster) are various species of short-horned grasshoppers in the family Acrididae that have a swarming phase. These insects are usually solitary, but under certain circumstances they become more abundant and change their behaviour and habits, becoming gregarious. No taxonomic distinction is made between locust and grasshopper species; the basis for the definition is whether a species forms swarms under intermittently suitable conditions; this has evolved independently in multiple lineages, comprising at least 18 genera in 5 different subfamilies.