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Identification of the Snakes of Illinois

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After the glaciers leveled northern and central Illinois, great prairies were created. Also, two large rivers meander through the state and forests grace the southern lands, which makes Illinois a diverse ecosystem that provides habitat for a wide variety of snakes. Illinois boasts about 40 different species of snakes, four of them venomous. Identification of poisonous vs. non-poisonous species may prove beneficial to both the snake's survival and your own.


Some Illinois snakes, like the plains garter snake, live in open prairies, while others like to hide in rocks near the rivers. Others, such as the red-bellied snake, find living conditions of the forests better suited to their needs. Some snakes, like the northern water snake or Kirtland's snake, live directly in streams, lakes, ponds and ditches. Marshes are home to a variety of snake species, such as the mud snake and the diamondback water snake. Learning the habitat of each snake species will assist you with species identification.

Venomous Snakes

Identification of venomous snakes is beneficial for obvious reasons. Typical identifying characteristics of venomous snakes are triangular heads, elliptical pupils and pits between the nostrils and the eyes. Four species of venomous snakes reside in Illinois: the stout-bodied, rusty-brown copperhead with hourglass patterns across its back, the large olive-black cottonmouth snake with dark banding on its back and an open white mouth when threatened, the gray-yellow timber rattlesnake with jagged cross marks on its back and a rattle on its tail, and the smaller spotted massasauga with four head stripes and a rattler tail.

Striped Snakes

Six different species of snakes residing in Illinois have horizontal body stripes: the western ribbon snake, plains garter snake, eastern ribbon snake, common garter snake, red-bellied snake and lined snake. Most are black with yellow striping, while the lined snake is olive-gray with white stripes. The red-bellied snake has red on its belly and head. The common garter snake is the most prevalent, followed by the eastern and western ribbon snakes, red-bellied snake and the rarely seen lined snake. Most are found in vegetation and forests near water, while lined snakes live in grasslands.

Red and Orange Snakes

A few snakes residing in Illinois sport colorful skin patterns. The scarlet snake and the milk snake have white bodies with large red-bordered black marks. The scarlet snake is smaller with more vibrant colors than the milk snake. The mudsnake has a black back with bright red and black striping on the underside. It is a large snake found living in or near swamps and ponds in southern Illinois. A diamondback water snake has a large, thick yellow to green body with black spots or crescents along its back. This snake is quick to bite and lives in quiet waters and swamps.

Green Snakes

Three different species of green-colored snakes live in Illinois. The rough green snake is a slender bright green snake with a white or yellow belly. Its head is wider than its neck and it's abundant in trees and bushes of southern Illinois. The smooth green snake is green with a yellow belly, but lives in the prairies and marshes of northern Illinois. The queen snake is a medium dark olive-colored snake with a yellow belly. It lives on the banks of unpolluted rocky streams in a few counties of central and northern Illinois.

Other Non-Venomous Snakes

A multitude of other spotted, patterned and plain-colored snakes live in Illinois. The worm snake, Graham's crayfish snake, eastern racer snake and plain-bellied water snake have scales in monotone blacks or browns. Other snakes, like the western hognose snake and gopher snake, have spots, while Dekay's brown snake is slate-gray with tiny brown spots. The ring-necked snake is a small burrowing blue-black snake that's easy to identify from its yellow neck band.