Adult uniformly black above and below, fading toward the reddish or tan tail. Rocky, open hillsides, glades, and hill prairies. If it cannot escape, it strikes and bites, often aiming for the face, and sprays feces and musk. Withstands dry habitats because it is quite resistant to desiccation. Mates in spring soon after emergence from hibernation and lays 4-24 eggs in summer.
Varied diet includes insects, lizards, other snakes, birds, small turtles, and small mammals.
It tracks prey by scent, following them into burrows or trees. Raptors, mammals, and other snakes are its main predators. Only one population known in southwestern Illinois. Its main threat is highway traffic.