Illinois Snakes Species Catalog & Expert’s Guide to Snake Safety

From the threatened and elusive Kirtland’s snake to the hardy and abundant DeKay’s brownsnake, this Midwestern state will surprise you with its snake diversity.

There are 40 species of Illinois snakes in total. Let’s take a look at the state’s four venomous species, the most frequently seen harmless species, and its most iconic snakes.

I’ll provide you with tips on how to stay safe around snakes, the best ways to coexist with them, and supply you with a list of helpful contacts at the end.

In Short

The highlights of what you’ll learn from this guide:

  • There are four species of venomous snakes in Illinois.
  • The best way to get over your fear of snakes is to educate yourself.
  • It’s best to give a snake its space and leave it alone if you see one in the wild.
  • 40 species of snakes call Illinois home, most of which belong to the Colubridae family.
  • Most snake bites result from people attacking, relocating, or pestering a snake in some way.
  • Snakes are way more beneficial than they are harmful; we need them to keep our ecosystem balanced.

Illinois Snake Identification Basics

There are several significant components to consider when identifying snakes.

The most important features include:

  • Size – Different species in Illinois range in maximum size, from less than a foot, to seven feet in length. Taking note of how long a snake is can help you distinguish it from similar-looking species.
  • Pupils – All venomous snakes in the state have elliptical pupils, while all of the non-venomous snakes have round pupils.
  • Location – Geographic location and habitat type will help you narrow down which snakes are likely to be in the area where you found the snake.
    Some snakes have specific habitat preferences. The Western ribbon snake, for example, prefers wet habitats and is only found along the Mississippi River in Illinois.
    There are many snakes in Southern Illinois that you won’t encounter anywhere else in the state. If you’re looking at snakes in Northern Illinois, they definitely won’t be species like the great plains rat snake or red-bellied mud-snake.
  • Coloration – A snake’s pattern and coloration are some of the most valuable identifiers, yet they can also be deceiving. You definitely won’t mistake a solid green species like the smooth green snake for a patterned rattlesnake species. However, it’s easy to mix up species like the lined snake, plains garter snake, and common garter snake.

You’re most likely to successfully identify a snake when combining all of these attributes.

Because snake characteristics often vary geographically, this guide is only for Illinois snake Identification.

Quickly Identifying Illinois Venomous Snakes

All venomous snake species in Illinois are pit vipers. They belong to a group of venomous snakes called the Viperidae family.

Pit vipers share traits that make them easily distinguishable from the harmless snake species of Illinois.

They all have:

  1. Elliptical pupils – Vertical pupils shaped like cat eyes
  2. Heat-sensing pits – Large sensory pits between each eye and nostril to help the snake locate prey
  3. Broad, triangular heads – Heads widened by venom glands behind the jaw
  4. A single row of scales under the tail – Most harmless species have two rows of scales on the underside of the tail

Fun Fact: People often mislabel these species as poisonous snakes in Illinois. However, poison is something you ingest.

Copperhead

Northern Copperhead Snake with its tongue out on top of a wood and green leaves on the side
The copperhead frequents abandoned sawdust piles.
Scientific Name: Agkistrodon contortrix
Range: Southern third of Illinois, in the Lower Illinois River valley

You may find these snakes in Central Illinois

Adult Size: 24-36 inches
Description: Heavy-bodied

Elliptical pupils and sensory pits on a broad head

Copper-red head, rusty-brown or yellow-brown body, keeled scales, reddish-brown hour-glass shaped bands

Juveniles have a green tail tip

Habitat: Woodlands, rocky hillsides, and along forest edges
Diet: Diet generalist, mainly mice, but also birds, lizards, other snakes, insects, and amphibians
Venomous/Non-Venomous: Venomous

Cottonmouth

Cottonmouth crossing a road
The cottonmouth is a semi-aquatic species.
Scientific Name: Agkistrodon piscivorus
Range: Tip of Southern Illinois
Adult Size: 30-42 inches
Description: Flat, wide head

Elliptical pupils and heat-sensing pits

Thick-bodied with keeled scales

May have dark bands or be solid black or brown

Juveniles have a green tail tip

Habitat: Swamps, sloughs, and lakes
Diet: Mice, fish, birds, lizards, amphibians, insects, and other snakes
Venomous/Non-Venomous: Venomous

Timber Rattlesnake

Timber Rattlesnake on top of dead leaves
The timber rattlesnake is the largest venomous species in Illinois.
Scientific Name: Crotalus horridus
Range: Southern third of Illinois and along the Mississippi River in the west

Found in the lower Illinois River valley and the Mississippi River valley

Adult Size: 36-60 inches
Description: Distinct rattle at the end of the tail

Elliptical pupils and sensory pits on a flat, wide head

Gray or yellow with dark, V-shaped bands, a rust-colored dorsal stripe, and keeled scales

May have a dark line between the eye and jaw

Habitat: Forested bluffs, rocky outcroppings, and fields
Diet: Rodents, birds, frogs, and lizards
Venomous/Non-Venomous: Venomous

Massasauga

Eastern Massasauga showing its rattle with a rock and grass in the background
The Eastern Massasauga, like many other snakes, takes advantage of crayfish burrows for shelter.
Scientific Name: Sistrurus catenatus
Range: Northern two-thirds of Illinois

The only venomous species not found in Southern Illinois

Adult Size: 18-30 inches
Description: Keeled scales

Rattle at the tip of the tail

Elliptical pupils and a wide head typical of pit vipers

Gray body with dark blotches down the back and three rows of dark spots along the sides

Habitat: Wet prairies, bogs, and fields
Diet: Mice, birds, frogs, and other snakes
Venomous/Non-Venomous: Venomous

Most Common Snakes in Illinois

Out of the 40 species of Illinois snakes, the most common snakes in Illinois, in order of most to least abundant, are the:

  1. Common Garter Snake
  2. Northern Cottonmouth
  3. Dekay’s Brownsnake
  4. Common Watersnake
  5. Plains Garter Snake
  6. Gray Rat Snake

Common Garter Snake

True to its name, the common garter snake is the most prevalent garter snake in Illinois. There are three other species native to the state.

Garter Snake surrounded by green and dead grass
Garter snakes are one of few hardy snake species capable of withstanding the chilly Northern Illinois climate.
Scientific Name: Thamnophis sirtalis
Range: Statewide
Adult Size: 18-26 inches
Description: Round pupils

Thin snakes with keeled scales

Three yellow stripes run down a black, brown, or green body

Habitat: A variety of habitats, including woodlands, meadows, marshes, along streams, and urban areas
Diet: Earthworms, insects, amphibians, mice, and birds
Venomous/Non-Venomous: Non-venomous

Dekay’s Brownsnake

If you’re a gardener, you’ll want brownsnakes around. These little snakes help keep pesky slugs and insects under control.

Dekay's Brownsnake on top of dead grass with some green grass around
Many animals eat brown snakes, including frogs, toads, birds, mammals, and other snakes.
Scientific Name: Storeria dekayii
Range: Statewide
Adult Size: 9-13 inches
Description: Keeled scales and round pupils

Brown or gray with a lighter dorsal stripe bordered by black dots

Habitat: Urban areas and a variety of wet habitats, including floodplains, marshes, swamps, prairies, and woodlands
Diet: Insects, slugs, and earthworms
Venomous/Non-Venomous: Non-venomous

Common Watersnake

There are five species of water snakes in Illinois. The common watersnake is the only one that occurs throughout the entire state.

Common Watersnake basking on top of a rock near water
Water snakes are often seen basking on rocks, logs, and vegetation near water.
Scientific Name: Nerodia sipedon
Range: Statewide
Adult Size: 22-42 inches
Description: Round pupils

Gray to dark brown with keeled scales

May have reddish-brown or black markings, or no pattern at all

Habitat: Natural and man-made bodies of water, including lakes, ponds, streams, marshes, and ditches
Diet: Fish and amphibians
Venomous/Non-Venomous: Non-venomous

Plains Garter Snake

Plains garter snakes are cold tolerant, and you may see them on warmer days throughout winter.

Plains Garter Snake on top of sand
You can often find plains garter snakes near sources of water, but also in urban areas.
Image credit: Andrew Hoffman via creativecommons.org
Scientific Name: Thamnophis radix
Range: Northern half of Illinois
Adult Size: 15-28 inches
Description: Round pupils on a small, pointed head

Brown, black, or green body with keeled scales

Yellow or orange dorsal stripe with a yellow-gray stripe on each side and black bars on the lips

Habitat: Fields, marshes, meadows, and river valleys
Diet: Amphibians, fish, small mammals, birds, earthworms, and other invertebrates
Venomous/Non-Venomous: Non-venomous

Gray Rat Snake

Areas with large rodent populations often attract gray rat snakes.

Gray Ratsnake with its tongue out surrounded by grass and twigs
Rat snakes are excellent climbers.
Image credit: Will Brown via creativecommons.org
Scientific Name: Pantherophis spiloides
Range: Southern two-thirds of Illinois
Adult Size: 42-72 inches
Description: Weakly keeled scales along the back

Round pupils on a head slightly wider than the neck

Coloration is variable, from solid black, to gray, or brown with a blotched pattern

Black and white checkered pattern on ventral scales

Habitat: Woodlands, farmland, shrubs, and thickets
Diet: Known for consuming rodents, but also other small mammals and birds
Venomous/Non-Venomous: Non-venomous

Iconic Illinois Snake Species

There’s something to appreciate about every snake, but there are a few exceptional snakes found in Illinois that you must see.

Take a look at these iconic snake species that call Illinois home.

Hognose Snakes

There are two species of hognose snake in Illinois, the Western and Eastern hognose snakes.

The Western hognose snake is listed as threatened in the state of Illinois. It has a habitat preference for sand prairies and mostly lives along the central Illinois River and the upper Mississippi River.

Its specialized habitat choice leaves it vulnerable to habitat destruction.

The Eastern hognose snake lives throughout the state. Like the Western hognose, it prefers habitats with sandy and loose soil.

Its coloration is widely variable. Individuals can be olive, brown, black, gray, tan, orange, or red. They often have dark blotches, but may also appear patternless.

Eastern Hognose Snake coiled on top of sand  with dead leaves around
The curved tip of a hognose snake’s nose helps it burrow and dig for prey.
Image credit: 2ndPeter via creativecommons.org

Hognose snakes have unique defensive displays. When threatened, a hognose widens its neck, inflates its body, and lets out a long hiss, earning them the nickname “puff adder”.

If this tactic doesn’t do the trick, a hognose will resort to faking its own death. It rolls over, twitches, lets its tongue hang out of its open mouth, and emits a foul smell.

Eastern Kingsnake

You might hear the Eastern kingsnake called the common kingsnake or chain kingsnake.

Kingsnakes are ophiophagous, meaning they eat other snakes, including venomous species.

Eastern Kingsnake coiled  on top of rocks with flowers and grass in the background
You can find these snakes in the Southern half of Illinois.
Image credit: 2ndPeter via creativecommons.org

The Eastern kingsnake may be confused with other black snakes in Illinois, like the North American racer and gray rat snake.

The Eastern kingsnake has smooth, shiny scales, speckled with white or yellow dots that form a chain-like pattern.

Some individuals may appear solid black, and others may have narrow bands.

Red-Bellied Snake

It may look drab from above, but take a closer look, and you’ll see its shockingly bright orange-red belly.

Red-Bellied Snake surrounded by dead leaves and twigs
The red-bellied snake (Storeria occipitomaculata) is closely related to the more common DeKay’s brownsnake.
Image credit: Andrew Hoffman via creativecommons.org

The red-bellied snake is a small species, averaging 8 to 10 inches long.

It prefers moist woodland habitats and mainly eats earthworms and slugs.

When threatened or consuming prey, they exhibit an unusual lip-curling behavior, showing their small teeth.

Snakes Native to Illinois

There are 40 species of Illinois snakes.

While there are many different types of snakes in the state, all but four species are part of the world’s most inclusive snake family, the Colubridae family.

The remaining species are the four venomous snake species, which belong to the Viperidae family.

Below is a comprehensive list of every species found in Illinois, organized by genera.

Some genera are well represented, with multiple species occurring within state lines, like the garter snake genus (Thamnophis).

Other species, such as the lined snake, are the only representatives of their genus in the state.

Racers

  • North American Racer Coluber constrictor

Mud Snakes

  • Red-Bellied Mud Snake Farancia abacura

Rat Snakes

  • Gray Rat Snake Pantherophis spiloides
  • Eastern Fox Snake Pantherophis vulpinus
  • Western Fox Snake Pantherophis ramspotti
  • Great Plains Rat Snake Pantherophis emoryi

Worm Snakes

  • Common Wormsnake Carphophis amoenus
  • Western Wormsnake Carphophis vermis

Kingsnakes

  • Prairie Kingsnake Lampropeltis calligaster
  • Eastern Kingsnake Lampropeltis getula
  • Eastern Milksnake Lampropeltis triangulum

Massasaugas

  • Eastern Massasauga Sistrurus catenatus

Earth Snakes

  • Smooth Earthsnake Virginia valeriae

Green Snakes

  • Rough Green Snake Opheodrys aestivus
  • Smooth Green Snake Opheodrys vernalis

Lined Snakes

  • Lined Snake Tropidoclonion lineatum

Rattlesnakes

  • Timber Rattlesnake Crotalus horridus

Water Snakes

  • Common Watersnake Nerodia sipedon
  • Southern Watersnake Nerodia fasciata
  • Plain-Bellied Watersnake Nerodia erythrogaster
  • Diamond-Backed Watersnake Nerodia rhombifer
  • Mississippi Green Watersnake Nerodia cyclopion

Garter Snakes

  • Plains Garter Snake Thamnophis radix
  • Common Garter Snake Thamnophis sirtalis
  • Eastern Ribbon Snake Thamnophis sauritus
  • Western Ribbon Snake Thamnophis proximus

Gopher Snakes

  • Gopher snake Pituophis catenifer

Scarlet Snakes

  • Northern Scarlet Snake Cemophora coccinea

Hognose Snakes

  • Eastern Hognose Snake Heterodon platirhinos
  • Western Hognose Snake Heterodon nasicus

Crayfish Snakes

  • Queen Snake Regina septemvittata
  • Graham’s Crayfish Snake Regina grahamii

Centipede Snakes

  • Flatheaded Snake Tantilla gracilis

Coachwhip Snakes

  • Coachwhip Masticophis flagellum

Kirtland’s Snake

  • Kirtland’s Snake Clonophis kirtlandii

American Moccasins

  • Copperhead Agkistrodon contortrix
  • Cottonmouth Agkistrodon piscivorus

Ring-Necked Snakes

  • Ringneck Snake Diadophis punctatus

American Brown Snakes

  • Red-bellied Snake Storeria occipitomaculata
  • Dekay’s Brown Snake Storeria dekayii

What You Need to Know

Snakes are a fundamental part of the Illinois ecosystem.

They’re a food source for many animals, including mammals, birds, other reptiles, frogs, and fish.

Snakes also keep pest populations in control by consuming rodents, insects, and other invertebrates that cause damage and spread disease.

This balance makes them invaluable to farmers, gardeners, and homeowners.

Snakes help prevent the spread of disease by consuming sick animals or animals that host Lyme disease-carrying ticks.

Educating yourself on snakes and their natural history is the best way to overcome any fears you may have.

We must coexist with these incredible creatures. They aren’t out to get you as their reputation leads you to believe.

Snake Safety

Venomous Snakes

Venomous snake bites are rare in the United States and even more so in Illinois.

Compared to states like Texas, Illinois has a meager amount of venomous snakes.

While the scarlet snake and milk snake may try to fool you, the venomous coral snake doesn’t live in this state.

If you do encounter one of the four venomous species found here, keep your distance, and you’ll be fine.

Snakes primarily use their venom for subduing prey. They’ll typically use other defensive mechanisms to scare you off before resorting to biting.

For more information on what to do if a venomous snake bites you, visit the Illinois Poison Center’s website.

Treading Carefully in Snake Habitat

There are several ways you can prepare yourself when entering potential snake habitats.

The best practices for staying safe include:

  • Stay on well-worn or paved paths.
  • Wear sturdy shoes and long pants.
  • Watch where you step, reach, and sit.
  • Keep your pets on a leash and watch where they put their noses.

Snakes like to hide under rocks, wood piles, debris, tall grass, and vegetation.

If You Encounter a Snake

If you come across a snake in the wild, don’t panic.

Snakes are generally shy creatures and want to be left alone. Give it space, leave the area, or allow it to depart on its own.

Most snakes will try to get away as quickly as possible if you get too close. However, some rely on their excellent camouflage skills to avoid predators (you).

Pit vipers are prone to staying as still as possible to hide in place, making it easier to step on them.

Besides the accidental misstep, the most common causes of snake bites are people attempting to handle, relocate, or injure a snake.

It’s best to leave wildlife alone.

When to Call for Help

The only times you’ll need to call for help are if you or your loved ones are in danger.

It’s illegal to remove native snakes without a permit in Illinois. Contact your local animal control or a licensed wildlife trapper if you need a snake removed from your property.

If a venomous snake bites you, contact 911 immediately.

Antivenom is most effective when administered within a few hours, so don’t wait for symptoms to appear.

Seek emergency veterinary care if a venomous snake bites your pet. Most pets survive if treated quickly.

Useful Resources

Emergencies

Illinois Poison Center Helpline: 1-800-222-1222

Free Snake Relocation Directory on Facebook

Pet Emergencies

American Society for the Prevention of Cruelty to Animals (ASPCA) Animal Poison Control Center 888-426-4435

Pet Poison Hotline 800-213-6680

Additional Information

The Illinois Department of Natural Resources Wild About Illinois Snakes!

The University of Illinois species lists.

Articles Related to Illinois Snake Identification

If you enjoyed learning how to identify snakes of Illinois, take a look at these guides:

Check out other articles our experts have written on snakes! You’re sure to learn something exciting.

Have you seen these snakes in the wild? Let us know in the comments!

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