Locusts 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.
Locusts, such as this migratory locust (Locusta migratoria), are grasshoppers in a migratory phase of their life.
Millions of swarming Australian plague locusts on the move
Desert locusts in copulation
Solitaria (grasshopper) and gregaria (swarming) phases of the desert locust
Grasshoppers are a group of insects belonging to the suborder Caelifera. They are amongst what are possibly the most ancient living groups of chewing herbivorous insects, dating back to the early Triassic around 250 million years ago.
Grasshopper
Fossil grasshoppers at the Royal Ontario Museum
Two differential grasshoppers, with visible spines along the tibia of the hind legs
Ensifera, like this great green bush-cricket Tettigonia viridissima, somewhat resemble grasshoppers but have over 20 segments in their antennae and different ovipositors.
