Illinois
Snakes in Cook County
15 species have been documented here, 1 of them venomous.
Venomous snakes in Cook County
Full guide & what to do if bitten →
Eastern MassasaugaSistrurus catenatusVenomousStout, dark-blotched body, nine large scales on the crown, and a small rattle.
Every snake recorded in Cook County
Common Garter Snake
Thamnophis sirtalis
Harmless
Plains Garter Snake
Thamnophis radix
Harmless
DeKay's Brownsnake
Storeria dekayi
Harmless
Common Watersnake
Nerodia sipedon
Harmless
Eastern Foxsnake
Pantherophis vulpinus
Harmless
Smooth Greensnake
Opheodrys vernalis
Harmless
Red-bellied Snake
Storeria occipitomaculata
Harmless
Eastern Milksnake
Lampropeltis triangulum
Harmless
Queensnake
Regina septemvittata
Harmless
Graham's Crawfish Snake
Regina grahamii
Harmless
North American Racer
Coluber constrictor
Harmless
Western Ribbon Snake
Thamnophis proximus
Harmless
Eastern Massasauga
Sistrurus catenatus
Venomous
Kirtland's Snake
Clonophis kirtlandii
Harmless
Common Ribbon Snake
Thamnophis saurita
Harmless
Compiled from verified GBIF & iNaturalist observations. Informational only.
Snakes in Cook County: FAQ
- Are there venomous snakes in Cook County, Illinois?
- Yes. 1 venomous snake species has verified records in Cook County, Illinois, including Eastern Massasauga. Most snakes in Cook County, Illinois, however, are harmless.
- How many snake species live in Cook County, Illinois?
- 10+ snake species have verified records in Cook County, Illinois, of which 1 is venomous.
- What is the most commonly seen snake in Cook County, Illinois?
- The Common Garter Snake is the most frequently reported snake in Cook County, Illinois, based on verified wildlife observations.
- What should I do if I see a venomous snake in Cook County, Illinois?
- Keep your distance and do not try to catch or kill it. Most bites happen when people handle or corner a snake. If someone is bitten, contact local emergency services or poison control immediately.