Illinois
Snakes in Johnson County
22 species have been documented here, 2 of them venomous.
Venomous snakes in Johnson County
Full guide & what to do if bitten →
Northern CottonmouthAgkistrodon piscivorusVenomousHeavy body, triangular head, vertical pupils, and a heat-sensing pit between each eye and nostril.
Eastern CopperheadAgkistrodon contortrixVenomousHeavy body, triangular head, vertical pupils, and a heat-sensing pit between each eye and nostril.
Every snake recorded in Johnson County
Northern Cottonmouth
Agkistrodon piscivorus
Venomous
Plain-bellied Watersnake
Nerodia erythrogaster
Harmless
Gray Ratsnake
Pantherophis spiloides
Harmless
Black Kingsnake
Lampropeltis nigra
Harmless
North American Racer
Coluber constrictor
Harmless
Common Watersnake
Nerodia sipedon
Harmless
DeKay's Brownsnake
Storeria dekayi
Harmless
Common Wormsnake
Carphophis amoenus
Harmless
Common Garter Snake
Thamnophis sirtalis
Harmless
Diamondback Watersnake
Nerodia rhombifer
Harmless
Ring-necked Snake
Diadophis punctatus
Harmless
Eastern Copperhead
Agkistrodon contortrix
Venomous
Rough Greensnake
Opheodrys aestivus
Harmless
Prairie Kingsnake
Lampropeltis calligaster
Harmless
Red-bellied Snake
Storeria occipitomaculata
Harmless
Smooth Earthsnake
Virginia valeriae
Harmless
Mudsnake
Farancia abacura
Harmless
Eastern Hognose Snake
Heterodon platirhinos
Harmless
Eastern Milksnake
Lampropeltis triangulum
Harmless
Western Ratsnake
Pantherophis obsoletus
Harmless
Eastern Kingsnake
Lampropeltis getula
Harmless
Western Ribbon Snake
Thamnophis proximus
Harmless
Compiled from verified GBIF & iNaturalist observations. Informational only.