jumping bean
Noun: A seed of certain Mexican shrubs, primarily of the genus Sebastiana (now often classified within Sapium). The seed appears to move or "jump" because it contains the live larva of a small moth (usually Cydia saltitans), whose movements cause the bean to jerk, roll, or tumble.
The term "jumping bean" is used to refer to the physical seed pod itself, which is a novelty item due to its perceived autonomous movement. - The children were fascinated by the jumping bean that seemed to dance on the table. - He brought back a handful of jumping beans from his trip to Mexico.
- The phenomenon is a form of zoochory, where animal activity aids in seed dispersal, though in this case it is involuntary and caused by the larva inside.
- The term is sometimes used metaphorically to describe a person who is very fidgety or unable to sit still.
- Sit down! You're like a jumping bean.
- Jumping bean moth (): The specific moth species whose larva inhabits the seed.
- Mexican jumping bean: A more precise common name, specifying the geographic origin.
- Mexican jumping bean (more specific synonym)
- Brincador (Spanish term meaning "jumper")
The "jumping" is an illusion created by the larva's movement as it shifts its weight or grips the inner wall of the seed and lets go, causing the pod to suddenly roll or flip. The bean itself is not alive; the movement comes entirely from the insect larva inside.
- seed of Mexican shrubs of the genus Sebastiana containing the larva of a moth whose movements cause the bean to jerk or tumble