A variety of snake species live in Pennsylvania, including three venomous species. Pennsylvania Herp Identification provides pictures and descriptions of all of the snake species found in the state. The Wilderness College provides a list of suggested identifying features to observe when trying to identify a snake species. Observe each individual characteristic and note possible species. Eliminate species as more characteristics are identified.
Observe the size of the snake
Small snakes under 1 foot in length could be red belly snakes, brown snakes, ring-necked snakes or earth snakes. Medium snakes up to 3 feet in length could be garter snakes, ribbon snakes, green snakes or queen snakes. Large snakes over 3 feet could be rattlesnakes, rat snakes, water snakes or racers.
Examine the color of the snake
Solid-colored snakes include green snakes, brown earth snakes and dark racer snakes. The ring-neck snake has a distinct ring of color around its neck. Snakes with stripes include garter, queen and ribbon snakes. Snakes with spots, blotches or bands include rattlesnakes, copperheads, rat snakes, milk snakes, water snakes and brown snakes.
Notice the shape of the snake's head
A triangular-shaped head usually indicates a venomous reptile. If the snake has a triangular head, a rattle and a pattern of V-shaped stripes, it is probably a timber rattlesnake. The other species of rattlesnake, the eastern Massasauga rattlesnake, has rounded markings. Copperheads have triangular-shaped heads, no rattles and a pattern of hourglass-shaped brownish stripes. Hognose snakes may flatten their heads out into a triangular shape, but they are a more uniform color than rattlesnakes and have no rattle. Small snakes with a distinct, small head are usually garter snakes. Large snakes with a large round head are usually water snakes.