Surprising Things You Should Know about Mexican Jumping Beans

Things You Should Know about Mexican Jumping Beans
Unlike what their name suggests, the Mexican jumping bean is not a bean! It is produced by a deciduous shrub known as Sebastiana pavoniana that grows on desert slopes in the states of Sonora and Chihuahua, Mexico.
Gardenerdy Staff
Last Updated: Feb 8, 2018
Did You Know?
When the stems of Mexican jumping bean shrubs are cut, it exudes a toxic milky sap. Many native Indian tribes use this sap to poison their arrow tips. In Mexico, the shrubs are sometimes called yerba de la flecha, which means 'herb of the arrow'.
Mexican jumping beans, also known as Frijoles saltarines, are seeds that have been populated by the larvae of a moth called Cydia deshaisiana. These beans are mainly found in the mountainous regions of the states of Sonora, Sinaloa, and Chihuahua. The moth lays eggs on the plant of genus Sebastiana. These plants have dark green leaves that turn red in winter. They are found in Mexico and parts of America. The eggs hatch and the larvae stay inside the seed pod and feed. When the plant matures, the bean turns brown in color. It is because of the moth's larva that the bean appears to jump. The moth that emerges, does not harm the environment. The beans are not poisonous. However, they are not considered as food.

Mexican jumping beans were sold in novelty shops in Mexico, where they are called brincadores. They were sold in novelty shops in the UK in the 1950s. They have become well-known in other parts of the world too, and are also sold in the United States. They are entertaining to watch and represent an interesting relationship between plants and insects.
Interesting Facts
Mexican jumping beans become active when they are exposed to light or heat.
Mexican jumping beans stop jumping after about 3 months as the larva inside the bean grows into pupa. It is the larva which makes the bean move. Six months later, an adult moth comes out of the bean.
The moth only lays eggs in the plant of genus Sebastiana that is found in Mexico.
The jumping movement of the Mexican beans lets the larvae move to a cool place to avoid the heat of the sunlight. Over exposure to heat will cause hem to die.
A well-developed moth does not emerge from every bean as many of the larvae die. This is due to lack of water. Generally, the moths do not cause any damage to the surroundings. However, they feed on fruits (pulp), thus making them unfit for human consumption. Due to this, they are considered as agricultural pests.
Mexican jumping beans are food for cats and dogs.
Mexican jumping beans are a good source of income for the Mexicans. They are abundantly available in summer.
Trivia
In the period between 1930s and 1950s, the Mexican jumping beans were used in many cartoons. Characters were shown eating these beans, which caused them to bounce uncontrollably.
Life Cycle
  • In the spring, the moth Cydia deshaisiana lays eggs in the ovaries or capsules of the flower of the shrub.
  • After the eggs hatch into the larva, it bores into the immature seed pod and ingests the interior of the pod or bean. It gets all its nutrition from the bean.
  • The larva attaches itself to the inside of the bean. The shrub ages, and the capsule hardens and turns brown.
  • By summer, the Mexican jumping bean shrub capsules divide, break open, and the seed is released. The carpels with moth larvae fall to the ground. The capsules that have larvae inside, start moving on the ground.
  • The larva jumps peculiarly inside the seed, which causes the seed to roll or tumble in different ways. The beans cannot jump above the ground.
  • The larvae secrete silk threads from their salivary glands. By taking hold of the silk lining with the forelegs, they transfer energy into the seed wall, which helps it roll over longer distances.
  • As winter arrives, the larvae start spinning a cocoon around themselves, inside the seed pod.
  • A Mexican jumping bean does not move during the winter months when the larva is in the process of growing into a pupa.
  • Following this, metamorphosis takes place and a silver and gray-colored moth comes out of a small trapdoor of the bean, which it drilled while entering it in the larval stage.
  • The moth can fly off and this life cycle repeats with another Mexican jumping bean.
  • The moths of the species exist in two sexual forms, egg-bearing females and sperm-bearing males.
How To Take Care of Mexican Jumping Beans
Handle Mexican jumping beans gently. Never throw them or they may die.
Mexican jumping beans should be drenched (but not immersed) in dechlorinated water for around 4 to 6 hours.
Arrange for a cool place like a refrigerator (not a freezer) or a room without sunlight for the Mexican jumping beans, when not handling them. This can help them survive longer.
Keep the jumping beans clean by rinsing them in water. Avoid soaps and other cleaning agents.
Hydrate the jumping beans occasionally by using a water sprayer. However, dry them later as mold may grow on them.
The jumping beans should not be fed with dairy products.
The jumping beans should not be tickled as they may move uncontrollably and land in inappropriate places.
Mexican jumping beans will keep moving (and entertaining you) for weeks or months if they are well taken cared of.
The Mexican jumping beans are an amazing example of a plant-insect relationship. However, it should be noted that this relationship is not mutualistic as the moth larva is only a seed predator and does not benefit the plant in any way.