Steven Carroll, age 9, of San Diego, CA , age 14, for their question:
What makes a jumping bean move?
A moving bean is enough to make anyone curious and, year by year, the dumping bean, alias the Mexican jumping bean, alias the bronco bean is the subject of one of Andy's most popular questions. It is a long, long time since he has answered the question in the column. Many readers ask about the dumping bean and Andy hopes that they will not feel sad or mad because they were not selected in today’s column. Remember, you can ask Andy as many questions as there are jumping beans in all the world.
The story of the dumping bean begins in Central or South America. It is a two part story between a plant and an insect. The plant is a member of the Euphorbiaceae family. These plants are also known as the spurges. The castor oil plant is a spurge and so is the dainty snow on the mountain which grows in the garden. The handsome, red leafed poinsettia is also a spurge. Most of the spurges have a milky .white sap and some of them that grow in the tropics produce a latex which can be used to make a rubbery substance.
These spurges, however, are merely cousins of the dumping bean spurges which grow in Central and South America. These are trees or bushes which blend in with other scrawny desert vegetation. As plants, we would hardly notice them. In spring, they produce small blossoms and these little flowers are certainly noticed by a certain gypsy moth.
The female moth seeks out the spurge blossoms when she is ready to lay her eggs. She is a small, grey insect and no one would notice her as she flies around, placing a single egg inside one, then another and another spurge blossom. Her work is now done and she exits from the story.
Soon the flower petals will fall and the moth eggs sleep safely inside the developing bean seed.
When each moth egg hatches, it finds itself inside a little bean. The young larva is small and the walls of its tiny prison are good to eat. As the bean grows bigger, the larva nibbles at the inside of its pantry walls. Both the bean and the grub grow bigger, but meantime the grub is eating a hollow room inside the bean. Soon the little fellow needs exercise. He coils his body in a spring and lets go with a jerk. We, of course, know what happens. Every tame the grub does his setting up exercises, he makes the bean jump.
The life of a larva must sooner or later come to an end. The larva 3n the jumping bean grows at last to his full size and becomes sleepy. Soon he becomes a pupa and the jumping bean jumps no more. Meantime the pupa is developing into an adult moth. When this job is finished, the moth hatches and escapes through a thin patch of wall at one end of the bean.