Harmless · Native to the United States

Common garter snake

Thamnophis sirtalis (Linnaeus, 1758)

Also called eastern garter snake, gartersnake
Data updated October 2026

Common garter snake in grass, showing three yellow stripes along a dark body with rows of black spots
Fig. 1 — Adult in grass, showing the three light stripes and checkered dark spots between them.
Close view of a common garter snake's head with large eyes and black bars on the lip scales
Fig. 2 — Large eyes and thin black bars between the upper lip scales.

At a glance

A slender, striped snake found across most of North America and often in backyards. It eats mostly frogs, toads and earthworms, bears live young in big litters, and is one of the first snakes out in spring.

01

Identification

Most common garter snakes have three light stripes running the length of a dark body: one down the middle of the back and one low on each side. The stripes are usually yellow but can be greenish, brown, blue or white, and the background is black, olive, brown or gray. Two rows of dark spots often sit between the stripes, giving a checkered look, and a few animals have hardly any stripes at all. Scales are keeled. Red-sided forms show red or orange skin between the side scales. Young look like small adults.

  1. 01Three stripes. One along the spine and one on each lower side, on scale rows 2 and 3.
  2. 02Checkered spots. Rows of dark blotches between the stripes, sometimes bolder than the stripes themselves.
  3. 03Barred lips. Thin black bars between the upper lip scales; ribbon snakes have plain lips.

Commonly confused with

02

Size

01 ft2 ft3 ft4 ft Typical adult · about 22 in (56 cm)

Most adults measure 18 to 26 inches (46–66 cm). Large ones occasionally reach about 4 feet; published maximums range from 42 to 54 inches depending on the region. Males have longer, thicker tails than females.

03

Range & habitat

Common garter snake basking at the grassy edge of a pond
Fig. 3 — Damp, grassy ground near water is classic garter snake habitat.

The common garter snake is one of the most widespread snakes in North America, found from southern Canada to Florida and across most of the continent, with separate subspecies from the Atlantic to the Pacific coast. It lives from sea level to high elevations and uses almost any habitat with cover: meadows, marshes, swamps, bogs, pond and stream edges, forest edges, hedgerows, ditches, vacant lots, farms, lawns and gardens. It prefers moist, grassy places but can wander well away from water.

State guides: Texas · Oklahoma · Florida

04

Diet & predators

Garter snakes hunt actively by sight and smell and swallow prey alive. Frogs, toads, tadpoles and salamanders make up most of the diet, followed by earthworms. They also eat slugs, snails, insects, small fish, nestling birds, mice and small snakes. Their saliva appears to be mildly toxic to frogs and other small prey. Being small and common, garter snakes are in turn eaten by a long list of predators, and the young are especially vulnerable.

Feeds on

  • Frogs, toads and tadpoles
  • Earthworms, slugs and snails
  • Salamanders
  • Small fish and mice

Preyed on by

  • Hawks, owls, herons and crows
  • Raccoons, foxes, skunks and cats
  • Kingsnakes, racers and copperheads
  • Bullfrogs and large fish
Small frog sitting at the edge of a pond
Prey — frogs.
Red-tailed hawk perched on a branch
Predator — hawks.

05

Behavior & seasons

Garter snakes are shy and usually slip into vegetation or under rocks when approached. Cornered, one may flatten its head and body and strike, and when picked up it often bites and smears a foul-smelling musk. The teeth are long for the snake’s size, so a bite can sting, but it is not dangerous; a few people react with mild local swelling or a rash. They hunt mostly by day, and also at dusk and night in hot weather and during frog breeding season.

They tolerate cold better than most snakes, so they are among the first out in spring and the last to den up in fall. In Missouri they are active from about March to early November and may surface on mild winter days. Winter is spent in groups in mammal and crayfish burrows, rock crevices, stump holes, old foundations and similar shelters. When are snakes active in Texas?

06

Reproduction

Common garter snakes bear live young. Mating takes place right after spring emergence in March or April, sometimes with several males courting one female in a “breeding ball,” and occasionally in fall. Young are born from July to October after about three months. Litters usually hold 10 to 40 young, with records from 4 to 85. The newborns get no parental care. Females can breed at about two years old, and garter snakes can live 10 years or more.

07

Conservation

As a species the common garter snake is abundant and secure across most of its range, helped by its broad habitat use and large litters. One subspecies is a major exception: the San Francisco garter snake, found only on the San Francisco Peninsula of California, has been federally listed as endangered since 1967 because of habitat loss, illegal collecting and invasive predators such as bullfrogs. Georgia protects all of its nonvenomous snakes, garter snakes included.

08

In captivity

Garter snakes are commonly kept as pets because they are small, active by day and easy to find captive-bred. An adult needs a secure, escape-proof enclosure with hiding places and a water dish large enough to soak in. In captivity they are fed foods close to their wild diet, such as earthworms and fish, and some accept small rodent items.

Rules on keeping wild-caught snakes vary by state, and some states, such as Georgia, protect native nonvenomous snakes. The San Francisco garter snake is federally endangered and may not be collected or kept.

Keep reading

Sources

Data updated October 2026 · How we build these pages