You shouldn’t hold a jumping bean for too long because it will kill the caterpillar that lives inside the bean. When the beans are in hot temperatures the caterpillars inside the beans jump to cooler temperatures to stay alive. When your hands close around a bean, it gets hot. The caterpillar inside tries to hop to cooler temperatures but it is enclosed by your hand which makes it impossible to escape. The heat from your hand can kill the caterpillar inside the bean.