Milk Snakes: Colored for Danger, but Totally Harmless (and Non-dairy!)

By: Mark Mancini  | 

milk snake
The pueblan milk snake (Lampropeltis triangulum campbelli), while harmless to humans, will feed on prey such as mice, rats, birds, lizards, frogs and other snakes. Joe McDonald/Getty Images

Got milk? Don't bother giving it to a milk snake. A lot of animals are named after things they sometimes eat — anteaters eat ants, dung beetles feed on you-know-what, et cetera, et cetera.

Then we have the milk snakes, a vibrant bunch of North American serpents with no interest whatsoever in dairy products, despite their common name.

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Udder Nonsense

"Like many snakes, milk snakes are generalist predators that eat just about anything they can catch and swallow," herpetologist Trevor Persons tells us in an email. "In general, younger, smaller milk snakes consume smaller prey such as lizards, while older, larger snakes primarily eat small mammals such as mice or voles."

Rodents like to take refuge in barns, capitalizing on the warmth and food they may provide. And where the furry critters go, their predators follow.

According to Persons, the name "milk snake" (sometimes written out as one word) "originated from the mistaken belief that since these snakes were frequently found in or around dairy barns, they were stealing milk from farmers by suckling on dairy cows."

Let the record show that snakes do not naturally consume milk. Let it also show that any real cow would most definitely notice and object to a sharp-toothed reptile clamping down on her udders.

The absurdity of that image was not lost on Karl P. Schmidt, a former curator of herpetology at the Chicago Field Museum. As he pointed out way back in 1922, milk snakes have six rows of needle-like teeth — two on the lower jaw, four on the upper one.

Jabbing these into "a cow's sensitive teat" (Schmidt's words, not mine) probably wouldn't end too well for the snake. It might make an amusing Gary Larson comic, though.

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Hardy Creatures

Milk snakes are nonvenomous and pose no threat to humans. Unfortunately, throughout their range, they're often killed at the hands of people who mistake them for venomous species.

The snakes are widely distributed, occurring from sunny Ecuador to southeastern Canada. Yet finding them can be a real challenge in certain places.

Herpetologist and ecologist Brian Smith was the lead author of a 2003 study on the milk snakes of Black Hills National Forest in Wyoming and South Dakota.

"In South Dakota anyway, they are very rarely seen," Smith explains via email. "But they have been found in a lot of different habitats. So they're a real mystery here. I've seen or heard of four of them in 23 years' experience looking for reptiles in the Black Hills area."

Throughout the Americas, milk snakes have a reputation for not being too picky about their habitats. Some hang around in prairies; others frequent pinewood forests; a lot of them do A-okay in tropical places — or arid deserts.

milk snake
The Central American coral snake (Micrurus nigrocinctus) is a highly venomous snake whose markings are very similar to the milk snake.
DEA/C.DANI/I.JESKE/Getty Images

And if you're wondering whether milk snakes make good pets, the answer is yes. They are completely nonvenomous and considered shy and easy to handle. Just make sure they have plenty of hiding places and they will be happy and easy to care for. As they often eat small mammals and insects in nature, you will want to feed them pre-killed mice.

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A Colorful Debate

The milk snake color palette is pretty diverse.

Most of these snakes are covered in well-defined bands of red, black and white (or yellow) scales. But there are plenty of exceptions. Up in the mountain forests of Panama and Costa Rica, there's a population of milk snakes that turn solidly black as adults.

With their Yankee counterparts, it's a different story. "[Milk snakes] from the northeastern U.S. and southeastern Canada are duller and browner and the 'bands' are actually blotches because they don't extend all the way to the belly," says Persons.

Scientists have long debated how many milk snake species — and/or subspecies — are currently at large.

Persons explains that "as recently as the 1990s," researchers used to lump all the milk snakes of North, South and Central America into "a single wide-ranging species [Lampropeltis triangulum] with 25 subspecies."

Such broad consensus no longer exists. In 2014, the journal Systematic Biology ran a genetic study arguing there are actually seven distinctive species of milk snake. "However, not all taxonomists agree with that arrangement either," notes Persons.

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Mimicry or Coincidence?

Next time you're at the library, head for the biology section. Most field guides to North American reptiles compare milk snakes with unrelated New World coral snakes.

The latter are not to be trifled with. Coral snakes (or "coralsnakes") are elapids; they're part of the same family as cobras, mambas and sea snakes. To fight off predators, and kill their own prey, the creatures dish out potent venom through hollow fangs.

Certain coral snakes advertise this toxicity with brightly colored scales. It's pretty much the opposite of camouflage. By wearing eye-catching shades of yellow, red, black or orange, the reptiles send a clear message to other species: "Stay away! I'm dangerous."

"Although difficult to test, it is believed that the colorful patterns of many milk snakes ... evolved to mimic those of venomous coralsnakes," says Persons. "In this form of mimicry, known as Batesian mimicry, a harmless milk snake resembles a dangerous coralsnake and thus discourages potential predators who may have previously learned the hard way not to mess with a coralsnake."

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Hit the Road, Jack

Milk snakes can range in size from 14 to 69 inches (35.5 to 175 centimeters) long with the longest of the species found in Central and South America.

You may have heard the rhyme, "Red touch yellow, kill a fellow. Red touch black, it's friendly, Jack!" This is a reference to banding patterns.

Eastern coral snakes — which are 4-foot (1.2-meter) serpents found in the southeastern United States — generally have a combination of alternating red, black and yellow bands. In most cases, their yellow bands touch the red ones.

milk snake
The scarlet kingsnake (Lampropeltis elapsoides) has similar markings to some species of milk snake and coral snake, but with black scales separating the reds from the yellows.
R. Andrew Odum/Getty Images

The nonvenomous scarlet kingsnake is a close cousin of the "milks" indigenous to the same area. It's got red, yellow and black bands, too. But they're arranged differently, with black scales separating the reds from the yellows.

Catchy as it is, please bear in mind that the "red touch yellow" rhyme isn't foolproof.

Some dangerous coral snakes are almost entirely black, some have black bands touching red ones. On the other hand, there are a few perfectly harmless snakes out there — like the Sonoran shovel-nosed snake — with yellow-on-red scalation.

So if a colorful serpent crosses your path and you can't positively identify it, keep your hands off the animal. You'll both be better off.

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