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common gartersnake

common gartersnake (Thamnophis sirtalis)
Photo © Brad M. Glorioso

Features and Behaviors

The common gartersnake averages 18 to 26 inches in length. The name “gartersnake” comes from the striped appearance of the back, similar to that of the garters that were once commonly used to support men’s socks. The appearance is variable. There are usually three stripes on the back that are often yellow but may be other colors. The belly is green or yellow with two rows of indistinct black spots. The scales are keeled (ridged).

The common gartersnake may be found statewide in Illinois. This animal lives in meadows, marshes, woodlands, hillsides, stream edges and vacant city lots. The common gartersnake is terrestrial. Active during the day, it will climb and swim. It hides under vegetation, boards or other objects on the ground. When alarmed, it may flatten its body and release an unpleasant musk from glands at the base of the tail. It overwinters in rock crevices or in the burrows of other animals. Mating occurs in early spring. Young are born alive in the period late summer through early fall. The female gives birth to between 15 and 80 young at one time, depending on her size and age. This snake eats earthworms, frogs, toads, salamanders, insects, mice and small birds.

Illinois Range


​Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Family: Natricidae

Illinois Status: common, native