Garter snakes of Iowa

Iowa has 28 different species of snakes, including four venomous species.

(Read about the venomous snakes of Iowa here.)

Most people are familiar with the garter snake, a common type of non-venomous snake, which are harmless to humans.

Let's take a look at the two kinds of garter snakes that are native to Iowa:

Plains garter snake (Thamnophis radix)

These garter snakes are found throughout Iowa and can range quite a bit in appearance. They measure 14-43 inches in length and typically are brown or black with two alternating rows of black spots. However, some are actually olive green instead of brown or black, and some even have red on the sides.

When scared, the plains garter snake will give off a foul-smelling odor and will expel excrement to get predators to leave it alone. It may also hide its head and raise its tail, shaking it back and forth.

Plains garter snakes are diurnal, which means they are active during the day, and they are found in a wide variety of dry areas. You might see them in a prairie, in a grassy area like a park, in your backyard or by a forest.

These garter snakes are not constrictors, so they eat whatever they can overpower with their jaws --- worms, amphibians, mice and bird eggs. They may also eat dead animals that they find.

Common garter snake (Thamnophis sirtalis)

The common garter snake looks very much like the plains garter snake and is about the same size, growing 14-48 inches in length.

It has three longitudinal stripes on a brown or black body and can also have red on its sides or belly.

There are two subspecies of the common garter snake in Iowa, the eastern garter snake (pictured above) which usually has white, mint green, orange or red on the skin between the scales --- visible when the skin is stretched as the snake is eating. There is also the red-sided garter snake that has the red on the sides between the top and side stripes of yellow or cream.

The common garter snake can be found throughout Iowa. The eastern garter snake is more common on the eastern side, and the red-sided garter snake is more common on the western side of Iowa.

The common garter snakes like habitats a bit wetter than the plains garter snake, so you may find it by the edge of water. It is also found in prairies, forests, grassy areas like parks and backyards and on farmland, just like the plains garter snake.

The common garter snake may be more aggressive than the plains garter snake. It also releases a bad-smelling musk, but it is more likely to bite --- a non-venomous, usually painless bite.

Like the plains garter snake, these garter snakes are not constrictors, so they eat whatever they can overpower with their jaws --- worms, amphibians, mice and bird eggs. They may also eat dead animals that they find.