Thamnophis Radix – Plains Garter Snake

Thamnophis Radix - Plains Garter Snake in the united states information

The plains garter snake is a harmless snake species that is found throughout the Central United States and Canada. The snake is mostly dark with three yellow or orange longitudinal stripes along its body.


The base color of the plains garter snake is dark brown, black or olive green, often with severall small yellow or orange spots. Three thin cream-colored, yellow or orange longitudinal stripes run from the sides of the head to the tail, one along the spine, the other two along the sides. The belly is usually olive green with several black spots. Most specimen have several small yellow or orange spots on their head. The plains garter snake is often confused with the black/brown and yellow morph of the common garter snake.

Thamnophis Radix - Plains Garter Snake in Illinois adult black dark snake with yellow stripes or lines
A plains garter snake found in Illinois. Photo: Peter Paplanus


Plains gartersnakes are medium-sized snakes. Adult specimen reach an average length of 24-40 inches (60-100 cm). Females are generally larger than males.

Thamnophis Radix - Plains Garter Snake in the united states information
A small specimen found in Kansas. Photo: Nick Varvel

Hunting Behavior and Habitat

As the name suggests, the plains garter snake is often found in plains, grasslands, as well as on wasteland, arable land and wet meadows. It hunts various small animals such as earthworms, slugs and amphibians. The snake is often found near water and is also an excellent swimmer. Occasionally, the plains garter snake also feeds on small fish and other water-based animals.

While most snakes that are found in the Northern United States hibernate during the winter months and never leave their burrows, the plains garter snake is more cold-resistant. Even though the snake also hibernates during the colder months, it occasionally appears on the surface to bask in the sun on warm winter days.

Black and yellow stripes snake in North Dakota is the Plains Garter snake
A plains gartersnake found in North Dakota. Photo: Flickr


Garter snakes have a mildly toxic saliva that can cause a slight burning or itching sensation for humans or pets. Overall, a bite is not medically significant or dangerous. Due to the low levels of toxines, the plains garter snake is considered a nonvenomous snake species. Since the snake usually flees from any encounter with larger animals or humans, bites are very rare.

Plains Garter Snake range in the USA

In the United States, the plains garter snake occurs in Illinois, Indiana, Oklahoma, Wisconsin, Kansas, Missouri, North Texas, Montana, North Dakota, South Dakota, Northern Nebraska, Eastern Wyoming, Eastern Colorado, Northeastern New Mexico, Ohio, Minnesota, Iowa and Arkansas. The snake is also found in Canada.

Scientific classification of Thamnophis radix

  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Reptilia
  • Order: Squamata
  • Suborder: Serpentes
  • Family: Colubridae
  • Genus: Thamnophis
  • Species: Thamnophis radix

In the past, researcheers have distinguished between two subspecies of the Plains garter snake: the eastern garter snake (Thamnophis radix radix) and the western garter snake (Thamnophis radix haydeni). However, this classification has been dropped and currently, no subspecies are recognized.

Thamnophis Radix – Plains Garter Snake

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