Japanese Rat Snake

The Japanese rat snake, known locally as aodaisho, is one of the most widespread and commonly encountered snakes in Japan. It occurs across most of the Japanese archipelago and has a long history in local folklore.

It is non-venomous and generally harmless to humans, and is often tolerated or even welcomed around rural buildings for its role in controlling rodents.

In Japanese culture, the species has traditionally been viewed as a guardian spirit associated with household shrines and granaries.

Adults typically show an olive-green to bluish-gray ground color, sometimes with faint darker striping, while juveniles display a more blotched, contrasting pattern that changes with age.

• Smooth dorsal scales
• Moderately elongated head
• Round pupils
• Slender to moderately stout body
• Adults commonly range from about 1.0 to 1.9 m

This species occupies a broad range of habitats across Japan, including forests, farmland, grassland, and areas near human habitation such as barns, sheds, and rice paddies. It is found from Hokkaido south through Honshu, Shikoku, and Kyushu.

The Japanese rat snake is diurnal and a skilled climber, often seen ascending trees, walls, or rafters in search of prey and nesting birds. It is generally docile, though it may musk or bite mildly if roughly handled.

It feeds primarily on rodents, birds, and eggs, killing prey by constriction. It is oviparous, laying clutches of around 7 to 15 eggs in early summer.