Foods Garter Snakes Eat. Like all snakes, the 30+ unique species of garter snakes are strict carnivores. This means they don’t eat plant matter and subsist solely on meat from other animals.

Garter snakes are harmless, very common and beneficially feed on slugs, leeches, large insects and small rodents in North American gardens.

Garter snakes, however, are a gardener’s friend and are harmless to humans. They do, however, eat pests that wreak havoc in a garden — from slugs to small rodents, such as tick-invested mice.

Like water snakes, narrow-headed garter snakes are highly aquatic and eat fish. In strong river currents their namesake elongated heads reduce drag from the water as they strike out on prey.