15-45 inches. Sides tan to dark brown overlain by rows of black spots that may make the upper sides appear black; some individuals with red markings or distinct checkerboard pattern on sides; usually a prominent white, yellow or orange stripe down the back and a pale stripe on each side on the 2nd and 3rd scale rows above the ventral plates; underside dull white or pale tan to pale green with a row of black dots on each side; scales keeled and in 19 rows.
Garter snakes occur in most habitats, including suburban areas. Garter snakes will often flatten their heads into a diamond shape and spread their bodies to show the pattern of spots when agitated. They give birth to 9-38 young.
Most of Louisiana but known from very few localities west of the Red River and Atchafalaya Basin; absent from the marshes.