Like it or not, most people have seen a garter snake at some point. If they seem to be just about everywhere, it's because they are. 

Common garter snakes are the most common snakes across the entire United States, in part because they can thrive in urban and suburban areas in addition to more open space, according to Animal Diversity Web. That makes them a common sight in Illinois.

The common garter snake has 13 subspecies found in different parts of North America. Illinois is home to two of these subspecies — the eastern garter snake and the Chicago garter snake, according to the Illinois Department of Natural Resources.

Early spring is mating season for these snakes. Garter snakes are ovoviviparous, which means the females give birth to live eggs, because the eggs hatch in the females' bodies. Garter snakes can have as few as seven babies or are many as 85.

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The name game

Like many animals, garter snakes are named for their appearance. In their case, their name comes from their stripes, which look similar to garters men used to wear to hold up their socks, IDNR reports. 

Physical characteristics

Garter snakes are named for their stripes, but not all garter snakes have stripes, according to IDNR. Some have spots instead. Striped garter snakes have three stripes, and they are usually yellow. Rows of black spots can usually be seen between the yellow stripes. The underbelly of a garter snake is typically yellow or green. 

The difference between the Chicago garter snake and the eastern garter snake is apparent in its stripe pattern. On Chicago garter snakes, the yellow stripes are broken up by black crossbars that run vertically, IDNR reports. The eastern garter snake does not have these crossbars. 

In general, garter snakes are between 18 inches and 26 inches long, and the females are larger than the males. Garter snakes have keeled scales, which means they have a rough, ridged texture. Some snakes have unkeeled scales, which makes them smooth to the touch.

Where they live

Garter snakes are the most common snakes in North America, and one reason for that is because they can live in a wide variety of habitats and environments. In the United States, garter snakes can be found from the East Coast to the West Coast, although they are most common east of the Mississippi River, according to Pennsylvania State University. 

In Illinois, garter snakes typically live in grassy areas like meadows or even city and suburban lots and yards as well as marshes, woodlands and hillsides, IDNR reports. 

What they eat

Garter snakes are carnivores, and they have a varied diet. They eat earthworms, leeches, slugs, crayfish, snails and a variety of insects, small amphibians, small fish and small snakes, according to Animal Diversity Web. They also sometimes eat mice and other small rodents as well as small birds. 

Why they matter

In general, snakes help control populations of animals that humans consider pests, including rodents and insects, and this is true of garter snakes as well, according to Animal Diversity Web. In particular, garter snakes can help control the populations of some nuisance insects and mollusks. Many gardeners like having garter snakes nearby because they control the population of garden pests.