Bikōchū

The is an insect that was once used by the Aburame clan in the great ninja wars. It was becoming an endangered species, however, so they let it live in a special bug habitat, uninhabited by humans. Two of the female's distinguishing traits are its long nose and its blue eyes, but a giant bug-like creature that looks exactly like it is sometimes confused with the real thing. It also has an incredible sense of smell, stronger than even that of a dog.

The species only lays eggs once every few years during a certain breeding season; a day following a rainstorm. Soon after one hatches, it goes into the pupa stage. After this, it is not long before it metamorphoses into an adult. Bug users are drawn to the bikōchū because of the fact that the first scent that the beetle detects after its metamorphosis stays in its memory, so whenever it smells it again it tries to get to the source of the scent. This is what makes Bikōchū coveted, since it can be used as a formidable tracking device.

Trivia

 * Bikō, when written as 鼻孔, is the Japanese word for nostril.