Gartersnakes and ribbonsnakes are Indiana's only distinctively striped snakes and this is the most common and widespread species of the group. They vary in color from gray-green to dark brown and, in rare cases, entirely black (melanistic). Most Common Gartersnakes have a light brown to white dorsal stripe extending from just behind the head to the tail and lateral stripes that nearly merge with the light brown-tan underbelly. Though some large female Common Gartersnakes may exceed four feet (1.2 m) in length, most adults are under three feet (1 m).
Plains Gartersnakes occur in the northwestern corner of the state and have an orange dorsal stripe and black spots between the lateral stripes and the underbelly. Butler's Gartersnakes are smaller and seldom seen in Indiana. They have a relatively smaller head and an indistinct neck. Both Eastern Ribbonsnakes and Western Ribbonsnakes are slender, elongate snakes with much longer tails that are more often found around aquatic habitats. While Common Gartersnakes have lateral stripes on scale rows two/three (counted up from the belly scales), all other Indiana Thamnophis have lateral stripes on scale rows three/four. DeKay's Brownsnakes are superficially similar to young Common Gartersnakes, but lack distinct stripes.
Ecology and Conservation
Common Gartersnakes occur throughout Indiana and may be found in nearly any habitat, including urban and suburban lots, parks, yards, and gardens. These snakes are most abundant in grassy, open habitat with ample moisture; such as wet meadows and stream margins.
Several subspecies of the Common Gartersnake (Thamnophis sirtalis) are recognized. Indiana is home to the Eastern Gartersnake (T. s. sirtalis) throughout most of the state and the Chicago Gartersnake (T. s. semifasciatus) in the northwestern part of the state.