Common Eastern Garter Snake

Facts, Identification & Control

Latin Name

Thamnophis sirtalis

Appearance

The common garter snake is long and slender with a colorful and extremely variable appearance. The snake’s average length is 18-26 inches, but can grow up to four feet long. Its upper body can range from black, brown-grey, olive or red and there are normally three light stripes running along its length. These stripes can vary from yellowish to brown, green, blue, orange, gray or whitish, and are normally well defined, although they may occasionally be indistinct or even absent. The under parts of the common garter snake are usually cream or white.

Behavior, Diet & Habits

Common garter snakes are one of the first snakes to appear in spring and can be seen throughout the year, even on very warm winter days. Unlike other snakes, garter snakes do not lay eggs. Instead, they give live birth to up to 50 young. The common garter snake is an excellent swimmer and frequently hunts by swimming slowly along the margins of pools, often sweeping its open mouth from side to side and seizing its prey. It may also track prey on land by scent and by sight, or catch earthworms by locating and thrusting its snout into the worm tunnel below the soil level.

The common garter snake takes a diverse range of prey, including fish, tadpoles, earthworms, leeches, insects, slugs and crayfish. However, earthworms and amphibians often make up the majority of its diet. Large adults also prey on immature voles or mice.

Common garter snakes are found from the Atlantic to the Pacific coast, except for the dry deserts in the southwest. They are found in a wide variety of habitats, including meadows, marshes, woodlands and hillsides where they tend to prefer moist, grassy environments close to water. They are among the most commonly encountered snakes in suburban areas, provided there are protective locations such as debris piles, vegetation, logs or rocks nearby.

More Information

Although common garter snakes are not considered venomous, they have a gland above the upper jaw on either side of the mouth (corresponding to the venom gland of vipers and other venomous snakes) that produces very mildly toxic venom. In general, bites from garter snakes are harmless because these snakes lack fangs and thus cannot efficiently inject secretions. However, prolonged bites by western terrestrial and common garter snakes have caused swelling and localized bleeding in people, presumably because unusually large amounts of venom seep into the bite.

When snakes are a problem, the best course of action is to call a pest management professional (PMP) who has the tools and knowledge to address snake problems.

Eliminating or reducing their food supply and cover can discourage common garter snakes. Since vegetation and debris are major snake attracters, mow closely around homes and outbuildings, store firewood and lumber away from residences and reduce piles of rocks, leaves or other items that give snakes shelter. Seal cracks and crevices in buildings and around pipes and utility connections. Small areas where children might play can be protected from most snakes with a snake-proof fence. Use of ultrasonic sound emitters (snakes can’t hear, at least in high frequencies) or fake owls or hawk decoys do not work to repel garter snakes.