15-30 inches. Dark gray or dark olive to nearly black above with vague, dark longitudinal bands; dull yellow or pale tan below and on the lowermost scale row; underside with two rows of black spots. Entirely black individuals are occasionally found in the southeastern part of the State. The keeled scales are in 19 rows.
Crayfish snakes are chiefly nocturnal and inhabit swamps and bayous. They spend the day hidden in crawfish burrows, water hyacinths and damp leaf litter near shore. They give birth to 6-14 young.
Throughout the state except for dry, upland portions away from water, and the salt marshes.