Okay, so I was an easily amused child. I admit it.
They usually came in a little clear plastic boxes with f four or five beans in them. They are about the size of a kernel of corn or a small bean. Picture a little bean that moves a fraction of an inch every 15 seconds or so . . . pretty exciting stuff, huh? That's about as exciting as jumping beans get.
It wasn’t until I found out what they really were . . . and what mad them jump . . . that they became less cool. WAY less cool. Icky even.
The thing that makes these beans jump is a tiny moth larvae that lives inside the bean. The moth lays its eggs in the flower of the plant, and the eggs are incorporated into the seeds. The larvae then eat out the interior of the bean and live there. When the larvae move, so does the bean. Eventually, the larvae turn into moths that emerge from the beans to repeat the cycle. Unless, of course, their stuck in a little airless plastic box . . . then they just suffocate.