Spicebush Swallowtail Caterpillar - When the larvae are nearly ready to pupate, they turn a yellow-green color marked by two large black dots with a white highlight. The placement of these dots creates the illusion that the caterpillars are common green snakes which help the caterpillars to ward off predators, specifically birds. (image credit Jay Cossey)
It's a new item for Pokemon Black 2, it allows the wearer to instantly destroy everything in it's path while forcing all Pokemon nearby to become infatuated. Luckily they have a counter ability called Nuke.