Locusts are insects that have long legs, like spears. Locusta also means "lobster".

Thomas of Cantimpré in his Liber de natura rerum shows confusion about the nature of the locust, saying it could be a four footed animal, an insect, or even a plant (or all three). He disguishes between the four footed (rabbit-size) animal, which he says John the Baptist ate; the "locust-worm" which is small; and the locust plant that is eaten by monks around the Jordan River. This confusion was echoed in encyclopedias that copied Thomas's work.