Any of more than a dozen species of snakes (genus Thamnophis, family Colubridae) with a striped pattern that resembles a garter: usually one or three longitudinal yellow or red stripes, with checkered blotches between. Forms in which the stripes are obscure or lacking are called grass snakes. Found in gardens and vacant lots, garters are among the most common snakes from Canada to Central America. They are small (usually less than 24 in., or 60 cm, long) and harmless, though some will strike if provoked. They eat insects, earthworms, and amphibians.