Venomous snakes in Illinois

Venomous snakes living in Illinois

4species, plus 2 with rare records

Cottonmouth, Timber rattlesnake, Copperhead, Eastern massasauga. A bite from any of these is a medical emergency.

How to recognize them

• CottonmouthDangerous482 records, 8 counties
• Timber rattlesnakeDangerous132 records, 6 counties
• CopperheadMedically significant211 records, 10 counties
• Eastern massasaugaMedically significant313 records, 8 counties

Cottonmouth Agkistrodon piscivorus

• Heavy, dark olive to black body; bands fade with age
• Broad flat head with a dark stripe through the eye
• Swims with the whole body high on the water

Timber rattlesnake Crotalus horridus

• Dark V- or chevron-shaped bands across the back
• Black tail ending in a rattle
• Yellow, tan or dark phases; some are almost black

Copperhead Agkistrodon contortrix

• Copper to tan body with dark hourglass bands: wide on the sides, narrow on the spine
• Plain coppery head with no pattern
• Young snakes have a bright yellow-green tail tip

Eastern massasauga Sistrurus catenatus

• Gray or brown with large dark blotches down the back
• Small rattle
• Nine large plates on top of the head

Every venomous snake species known from the US is on this site.

Counties with records

Active months

Rare records

• Rare records Western diamondback rattlesnake 5 open records
• Rare records Western massasauga 1 open record

Harmless snakes people mistake for them

• Cottonmouth vs Water Snake Water snake: harmless
• Copperhead vs Northern Water Snake Northern water snake: harmless
• Copperhead vs Corn Snake Corn snake: harmless
• Copperhead vs Rat Snake Rat snake: harmless
• Copperhead vs Milk Snake Milk snake: harmless
• Cottonmouth vs Diamondback Water Snake Diamondback water snake: harmless
• Copperhead vs Hognose Snake Eastern hognose snake: harmless

• Water snakeHarmlessHarmless
• Northern water snakeHarmlessHarmless
• Diamondback water snakeHarmlessHarmless
• Eastern hognose snakeHarmlessHarmless
• Corn snakeHarmlessHarmless
• Rat snakeHarmlessHarmless
• Milk snakeHarmlessHarmless
• Gopher snakeHarmlessHarmless

Quick answers

• Lives here Are there rattlesnakes in Illinois?
• Lives here Are there copperheads in Illinois?
• Lives here Are there cottonmouths in Illinois?

More for Illinois

• All venomous animals in Illinois
• Venomous spiders in Illinois
• Scorpions in Illinois
• Centipedes in Illinois

Venomous snakes in neighboring states

• Iowa
• Indiana
• Kentucky
• Missouri
• Wisconsin