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Mexican jumping bean

Sebastiana pavoniana

Description:

Mexican jumping beans (also known as Frijoles saltarines), native to Mexico, are seed pods that have been inhabited by the larva of a small moth (Cydia deshaisiana). The "bean", usually tan to brown in color, "jumps" when heated, because the larva spasms in an attempt to roll the seed to a cooler environment to avoid dehydration and consequent death. They are from the shrub Sebastiana pavoniana, often also referred to as "jumping bean". However, they are not related to actual beans (legume plants), but rather to spurges. The beans are considered non-toxic, but are not intended to be eaten. And to say they jump is a bit of a stretch; it is more of a bit of modest twitching. Regardless, the successful promotion of the “Mexican jumping bean” is a triumph of insect marketing. Watch the videos to see them jumping..

Habitat:

Sonora State, Mexico. They were selling these Jumping beans in a local market in San Miguel de Allende, Mexico.This is where I saw them. http://youtu.be/F5dI0kczZS4

Notes:

The Mexican jumping bean moth, Cydia deshaisiana, is a small moth that lays its eggs in spring following the flowering of its host plant, Sebastiana pavoniana, a desert shrub native to mountainous areas in the northern Mexico states of Sinoloa and Sonora. Upon hatching the young larvae tunnel into the developing seeds and by late spring have completely consumed the interior of the seed. During the rainy season of summer, the seeds drop from the plant. The insects remain secure within the tough seed coat, the interior of which may also be covered in silk produced by the caterpillar. During this time, when suddenly warmed, as from the heat of a hand, the caterpillar inside the “bean” begins to twitch, causing the seed to move. Presumably this behavior is useful for preventing the insect from overheating on the desert floor; movements of the seed, with the insect inside, can shift the seed to shaded areas out of direct sunlight. The caterpillar remains within the seed through the rest of the year, but goes into a semi-dormant state (diapause) when full grown and ceases to feed.

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LuisStevens
Spotted by
LuisStevens

Valle Alcocer, Guanajuato, Mexico

Spotted on Oct 7, 2013
Submitted on Oct 7, 2013

Spotted for Mission

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