The color is reputed to change when the snake is agitated. They can vary from black to a mustard yellow, but are normally an olive green in appearance when young and dark olive when older, with the sides and underside distinctly lighter.
It's said that the color of these snakes changes when they're upset. Their hues can vary from black to a bright yellow, but they usually have an olive green appearance when they're younger and a darker olive tone as they mature, with the lighter-colored areas on their sides and belly standing out.