Corn snake vs rat snake

Two rat snakes, one name

Both snakes belong to the genus Pantherophis, the North American rat snakes^8,9. The corn snake is sometimes called the red rat snake, and its belly checks are said to have reminded people of the kernels of Indian corn^1,10. “Rat snake” on its own usually means the big black or grey snake of the eastern United States, which the 2025 standard list of North American names calls the central ratsnake, although many guides and state agencies still call it the eastern or black rat snake^7,9. The two look most alike as hatchlings, when both are grey with dark blotches, and least alike as adults^3,5.

Colour and pattern

An adult corn snake is orange to reddish-brown with 27–40 reddish blotches edged in black along the back⁵. Snakes from the coastal plain are the brightest orange; those from the Piedmont and uplands are darker and duller, and young snakes are browner or greyer⁵. An adult rat snake across most of its range is glossy black above with a white chin and throat, sometimes with faint traces of its juvenile blotches^3,6. In peninsular Florida the rat snake is instead yellowish with four dark stripes running the length of the body¹.

Young rat snakes are the problem. They hatch grey with 28–40 dark blotches and a dark stripe from the eye to the corner of the mouth, and they do not turn black until they are about 60 cm long, which can take four or five years^3,12. At that stage they are easily taken for young corn snakes, and the reverse.

The head and the belly

The surest mark is on the head. A corn snake has a spear-shaped mark that runs forward from the neck and meets in a point between the eyes, and a black-edged reddish stripe runs from the eye past the jaw onto the neck^1,2,5. Young grey rat snakes have no spear point between the eyes². Turn to the underside and the corn snake has a bold black-and-white checkerboard belly that continues as two black stripes under the tail^1,2. The black rat snake also has a black-and-white checkerboard belly, but it is irregular, greyer and fades towards the tail, and it has no tail stripes; Florida’s striped rat snakes have no checkerboard at all^1,3. Milksnakes and mole kingsnakes, which can also be confused with corn snakes, likewise lack the stripes under the tail^2,4.

Both species have weakly keeled scales and round pupils, and the rat snake’s body is flat-bottomed, like a loaf of bread in cross-section^1,3,6.

Size

The rat snake is the larger animal. Adult eastern rat snakes usually measure 1.07–1.83 m and the largest known was 2.56 m; it is Ontario’s largest snake, reaching about 2 m there^3,11. Adult corn snakes are usually about 0.9–1.2 m, with a record of 1.88 m^1,5. A big, glossy black snake is a rat snake, not a corn snake.

Where they overlap

The corn snake lives in the south-eastern United States, from southern New Jersey south through the Carolinas to the Florida Keys and west to eastern Louisiana, and it is found in every county of mainland Florida^1,5. The eastern rat snake covers a much larger area, from the Mississippi River east to the Atlantic and north to Wisconsin, Michigan, New York, Vermont and Massachusetts, and into southern Ontario^7,9,11. Across the south-east, where the two share pine woods, old fields, farms and barns, either may turn up in a shed or chicken house, because both hunt rodents and birds and both climb well^1,5,6.

Neither is venomous

Both are harmless to people. The corn snake is a constrictor that kills its prey by squeezing⁵, and the eastern rat snake is non-venomous too; if handled it may bite, release a foul musk or vibrate its tail, which is why it is best left alone⁶. The snake people most often mistake for a corn snake is the venomous copperhead, which has hourglass-shaped crossbands that are wide on the sides and narrow across the back, and lacks the corn snake’s checkerboard belly^4,10. Rat snakes do not interbreed with copperheads, whatever the old stories say; the two are only distantly related⁶.

These differences are not a safe basis for handling any snake. Keep your distance from every snake you cannot identify. Pet corn snakes are bred in huge numbers, and wildlife agencies advise never taking a wild snake as a pet or releasing a pet into the wild^6,10.