How Can You Tell if a Snake Is Dangerous?

Few things will send you scrambling to Google quicker than a snake sighting.

You may do so in fear or fascination, but you’re probably not indifferent to the issue. People tend to have strong feelings about snakes.

But no matter your motivation, I’m here to help you figure out whether the snake you saw was dangerous or not.

Fast Facts: How Can You Tell if a Snake is Venomous or Not?

Unfortunately, there is no simple way to distinguish venomous snakes from nonvenomous snakes.  

This includes all of the cute “rules,” songs and gimmicks you’ve heard.

They are all wrong in some cases.

The good news is that there are a finite number of venomous species in any given geographic area. So, you’ll simply have to learn to identify the ones native to your region.

Don’t get nervous — it’s usually not that hard.

Venomous Snakes of the United States: An Overview

There are roughly 20 species of venomous snake in the U.S.

I say “roughly” because different authorities embrace different taxonomies.

For example, one university may consider the timber rattlesnake to be a completely different species than the canebrake rattlesnake. Meanwhile, some other, equally prestigious institution may consider them to be different subspecies of the same species.

Taxonomy is an incredibly fluid discipline, and biologists reorganize the family tree of life (in very small ways) on a constant basis.

This usually isn’t a big deal for the average person, but it is part of the reason that lists of venomous snake species may differ in number.

Also, note that the terms “venomous” and “dangerous” are more subjective than you may think.

But we’ll get to that later.

For now, the list of venomous snakes in the United States:

  1. Eastern diamondback rattlesnake (Crotalus adamanteus)
  2. Western diamondback rattlesnake (Crotalus atrox)
  3. Mojave rattlesnake (Crotalus scutulatus)
  4. Sidewinder (Crotalus cerastes)
  5. Arizona black rattlesnake (Crotalus cerberus)
  6. Timber rattlesnake (Crotalus horridus)
  7. Black-tailed rattlesnake (Crotalus molossus)
  8. Tiger rattlesnake (Crotalus tigris)
  9. Ridge-nose rattlesnake (Crotalus willardi)
  10. Rock rattlesnake (Crotalus lepidus)
  11. Speckled rattlesnake (Crotalus mitchellii)
  12. Prairie rattlesnake (Crotalus viridis)
  13. Western rattlesnake (Crotalus oreganus)
  14. Twin-spotted rattlesnake (Crotalus pricei)
  15. Panamint rattlesnake (Crotalus stephensi)
  16. Red diamond rattlesnake (Crotalus ruber)
  17. Pigmy rattlesnake (Sistrurus miliarius)
  18. Massasauga (Sistrurus catenatus)
  19. Eastern coral snake (Micrurus fulvius)
  20. Texas coral snake (Micrurus tener)
  21. Western coral snake (Micruroides euryxanthus)
  22. Copperhead (Agkistrodon contortrix)
  23. Cottonmouth (Agkistrodon piscivorus)
  24. Yellow-bellied sea snake (Pelamis platurus)

But this list can’t help you by itself – no state is home to all of these species, and a few aren’t home to any.

But you can just consult the table below to determine which venomous snakes are native to your state.

A State-by-State Breakdown: Venomous Snakes of the U.S.

To find out which venomous snakes are found in your area, just find your state in the table below.

Alabama Copperhead, cottonmouth, eastern coral snake, eastern diamondback rattlesnake, timber rattlesnake, pigmy rattlesnake
Alaska None
Arizona Western coral snake, western diamondback rattlesnake, sidewinder, Arizona black rattlesnake, rock rattlesnake, speckled rattlesnake, black-tailed rattlesnake, western rattlesnake, twin-spotted rattlesnake, Mojave rattlesnake, tiger rattlesnake, western rattlesnake, ridge-nosed rattlesnake, massasauga
Arkansas Copperhead, cottonmouth, western diamondback rattlesnake, timber rattlesnake, pigmy rattlesnake, Texas coral snake
California Western diamondback rattlesnake, sidewinder, speckled rattlesnake, western rattlesnake, red diamond rattlesnake, Mojave rattlesnake, Panamint rattlesnake, yellow-bellied sea snake
Colorado Western rattlesnake, massasauga
Connecticut Copperhead, timber rattlesnake
Delaware Copperhead, timber rattlesnake
Florida Copperhead, timber rattlesnake, cottonmouth, eastern coral snake, pigmy rattlesnake, eastern diamondback rattlesnake
Georgia Copperhead, cottonmouth, eastern diamondback rattlesnake, timber rattlesnake, pigmy rattlesnake, eastern coral snake,
Hawaii Yellow-bellied sea snake
Idaho Western rattlesnake, prairie rattlesnake
Illinois Copperhead, cottonmouth, timber rattlesnake, massasauga
Indiana Copperhead, cottonmouth, massasauga, timber rattlesnake
Iowa Copperhead, massasauga, prairie rattlesnake, timber rattlesnake
Kansas Copperhead, timber rattlesnake, cottonmouth (controversial)
Kentucky Copperhead, cottonmouth, timber rattlesnake, pigmy rattlesnake
Louisiana Copperhead, cottonmouth, timber (canebrake) rattlesnake, pigmy rattlesnake, eastern diamondback rattlesnake, eastern coral snake, Texas coral snake
Maine None
Maryland Copperhead, timber rattlesnake
Massachusetts Copperhead, timber rattlesnake
Michigan Massasauga
Minnesota Timber rattlesnake, massasauga
Mississippi Copperhead, cottonmouth, timber (canebrake) rattlesnake, pigmy rattlesnake, eastern coral snake, eastern diamondback rattlesnake
Missouri Copperhead, cottonmouth, timber rattlesnake, pygmy rattlesnake, massasauga 
Montana Prairie rattlesnake
Nebraska Copperhead, massasauga, timber rattlesnake, prairie rattlesnake
Nevada Western diamondback rattlesnake, sidewinder rattlesnake, Great Basin rattlesnake, speckled rattlesnake, Mojave rattlesnake, prairie rattlesnake, western rattlesnake
New Hampshire Timber rattlesnake, copperhead
New Jersey Timber rattlesnake, copperhead
New Mexico Western diamondback rattlesnake, Arizona black rattlesnake, banded rock rattlesnake, black-tailed rattlesnake, Arizona black-tailed rattlesnake, Mojave rattlesnake, prairie rattlesnake, ridge-nosed rattlesnake, massasauga, western coral snake
New York Timber rattlesnake, copperhead, massasauga
North Carolina Timber rattlesnake, copperhead, cottonmouth, eastern coral snake, pygmy rattlesnake, eastern diamondback rattlesnake
North Dakota Prairie rattlesnake
Ohio Timber rattlesnake, copperhead, massasauga
Oklahoma Prairie rattlesnake, western diamondback rattlesnake, copperhead, massasauga, cottonmouth, timber rattlesnake, pygmy rattlesnake
Oregon Prairie rattlesnake
Pennsylvania Timber rattlesnake, copperhead, massasauga
Rhode Island None
South Carolina Timber rattlesnake, copperhead, cottonmouth, eastern diamondback rattlesnake, coral snake, pygmy rattlesnake
South Dakota Prairie rattlesnake
Tennessee Timber rattlesnake, copperhead, cottonmouth, pygmy rattlesnake
Texas Western coral snake, prairie rattlesnake, cottonmouth, copperhead, western diamondback rattlesnake, massasauga, timber rattlesnake, rock rattlesnake, black-tailed rattlesnake, Mojave rattlesnake
Utah Mojave rattlesnake, prairie rattlesnake, sidewinder, speckled rattlesnake
Vermont Timber rattlesnake
Virginia Timber rattlesnake, cottonmouth, copperhead
Washington Prairie rattlesnake
West Virginia Timber rattlesnake, copperhead,
Wisconsin Timber rattlesnake, massasauga
Wyoming Prairie rattlesnake, western rattlesnake

Mildly Venomous Species of the U.S.

The 24 species listed above are all typically regarded as dangerously venomous to humans. They all have enlarged fangs located at the front of their mouths, and these fangs are connected to venom glands via a distinct duct.

The bites from some, such as copperheads, rarely cause human fatalities, provided that the victim receives prompt medical attention. But a copperhead bite is still a medical emergency, which can cause severe tissue damage and further complications. Accordingly, their bites are still considered dangerous or “medically significant” for humans.

But in recent years, researchers have discovered some interesting things about the oral secretions, head anatomy and dentition of several species that are typically considered nonvenomous. The details are still the subject of considerable debate, but it appears that many of these species may, in fact, be venomous — depending on how you choose to define the term.

For example, many snakes traditionally considered to be nonvenomous have glands located near their mouths. These glands produce secretions that may aid in prey acquisition (and conceivably defense).

Some authorities consider these glands — called Duvernoy’s glands — and the secretions they produce to be analogous to the venom and venom glands of dangerous species. Others disagree, while still noting that the secretions produced by these glands aid in prey capture and/or digestion.

These are largely technical, academic distinctions, which are of little importance to the average person looking at a snake in the backyard. Most of these species should still be considered harmless to humans, as they’re either too small to effectively envenomate a human, they lack effective venom-delivering tools or their venom just doesn’t have the chemical characteristics necessary to cause serious reactions.

However, bites from these species may cause things like pain, tingling, numbness and swelling. So, while these species are unlikely to kill you, they still deserve respect and shouldn’t be handled in careless fashion.

A few of the most notable “mildly venomous” snakes native to the United States include:

Hognose Snakes

There are dozens of snakes that bear the “hognose” moniker, but those in North America are all members of the genus Heterodon. They have, as you may expect, an upturned nose (which is actually pretty darn cute).

There are three species in the genus found in the U.S., and they differ pretty significantly in terms of color and pattern. Also, while eastern (H. platirhinos) and southern (H. simus) hognose snakes are toad-eating specialists, the western hognose (H. nasicus) includes more rodents in its diet.

All three are famous for their death-feigning behavior when threatened, but they’ll also flatten their heads and necks, hiss loudly, and put on quite an aggressive display in some cases.

Hognose snakes have relatively large fangs, but instead of being situated near the front of the mouth, as they are in rattlesnakes and coral snakes, they’re located farther back in the mouth (more-or-less under the snake’s eye). In fact, the name of the genus – Heterodon – literally means, “different tooth,” and is a reference to these enlarged fangs.

Fortunately for humans, hognose snake venom appears to be most effective on amphibians, and it rarely causes serious problems for humans. There are some reports of individuals experiencing pain and swelling, but no deaths have ever been reported.

Additionally, hognose snakes are only rarely able to envenomate humans. They don’t often bite defensively, and their fangs are located too far back in their mouths to achieve really good penetration during a defensive bite.

Instead, most people envenomated by hognose snakes are breeders and pet owners who receive bites during feeding mistakes or when trying to force feed their snake.

Anecdotally, I’ve met a couple of keepers who’ve had the pleasure of pricking their finger on a hognose snake’s “toad poppers” (as they’re often called). Neither recommended the experience and both described it as very painful.

Black-Headed Snakes

There are 60-odd described species in the genus Tantilla, and a handful inhabit the U.S. They’re all quite small – a few species in South America may reach 2 feet in length or so, but most in the U.S. are less than 12 inches.

Black-headed snakes primarily hunt centipedes, spiders, scorpions, insects and worms, and their venom appears to be rather targeted at this type of invertebrate prey. But while these snakes are correctly characterized as being venomous, they’re likely completely harmless to humans, given their small size.

Lyre Snakes

Lyre snakes (Trimorphodon spp.) are represented by about a half-dozen species, who range from Nevada to Costa Rica. Most are found in relatively arid, rocky regions, where they prowl for lizards and rodents.

Lyre snake venom does not appear to cause serious reactions in most mammals (which is part of the reason these snakes often add constriction to the mix when feeding on rodents).

Nevertheless, lyre snakes grow larger than many of other “mildly venomous” species discussed here, as they reach about 3 feet in length. This means that even though their fangs are located in the rear portions of their mouths, they won’t have as much trouble bringing them to bear while biting a human.

Additionally, lyre snakes are a bit bolder than some of the other species described here, and they will not hesitate to bite if threatened.

Night Snakes

The night snakes (Hypsiglena spp.) are another group of rear-fanged species that produce venom yet are typically considered harmless to humans.

Nevertheless, at least one study showed that their venom produced swelling and pain in mammals (rodents).

But as with many other “venomous but essentially harmless” snakes, night snakes are small. Very few exceed 16 inches in length, which makes it difficult for them to bring their rear-positioned fangs into play while biting humans.

Ringneck Snakes

Named for the — get this — light-colored ring around their necks, ringneck snakes (Diadophis punctatus) are cute little buggers who spend their lives hunting for worms, salamanders, and other long, slimy things under rocks and logs.

They’re quite common in backyards, suburban parks and other disturbed habitats, and they often reach extraordinary population densities: A 1975 study in Kansas by famous herpetologist Henry S. Fitch found that the average population density of ringneck snakes in the study area was approximately 3,000 individuals per acre.

Across their range, which stretches from Canada to central Mexico and includes vast swaths of the United States, these snakes are represented by a more than one dozen different subspecies. Most of these species have enlarged teeth or fangs located in the rear of their mouths, and they produce oral secretions that help incapacitate prey.

Nevertheless, ringneck snakes are generally pretty placid, and they rarely offer to bite. When threatened, they often display their brightly colored ventral surfaces, and they may hold their tail up in a tight curl (which also exposes their brightly colored ventral surface).

Additionally, most ringneck snakes are small — 12 to 16 inches or so. This makes it very hard for them to bring their rear-positioned fangs into play when biting something as large as a human. However, the regal ringneck snake (Diadophis punctatus regalis) of the southwestern United States may approach 3 feet in length, which is likely large enough to achieve skin penetration with the fangs.

Red-Bellied Snakes

Some authorities suggest that red-bellied snakes (Storeria occipitomaculata) produce secretions from their Duvernoy’s glands that can arguably be described as venom. They’re likely far too small (they rarely exceed 10 inches) to effectively envenomate a human, but this “venom” may be helpful when trying to catch and subdue their preferred prey: snails and slugs.

In fact, red-bellied snakes exhibit a number of interesting adaptations that help them live on a diet of escargot.

For example, their skulls are thinner than many of their closest relatives, which may help them insert their heads farther into snail shells. Additionally, they have very long, thin teeth, which point toward the backs of their mouths. These surely help the snakes to grip and consume their slippery prey.

These snakes also appear to shift their movement patterns in response to changing water levels. Red-bellied snakes often live near the borders of small ponds and streams, where slugs and snails are common. But most interestingly, researchers working at the Savannah River Ecology Lab have found that these snakes follow the retreating water line as these water sources dry up.

Garter Snakes

Few snakes in the United States are more familiar to everyday people than garter snakes are — even if many get their common name wrong and call them garden or gardener snakes.

This confusion is understandable; after all, snakes of the genus Thamnophis are often found in gardens and beloved by gardeners for the ecological services they provide. But their common name is derived from the snakes’ dorsal stripes, which were reminiscent of garters often worn decades ago.

Most people in the U.S. have probably encountered a garter snake at some point in their lives. And in many cases, because they’re typically considered nonvenomous, these snakes often survive encounters with humans.

But in actuality, garter snakes — like the other species discussed here — do produce toxic secretions from their Duvernoy’s glands, which can arguably be considered venom. These secretions don’t appear to be particularly dangerous for humans, though they probably are effective on some of the species garter snakes routinely consume.

It is important to note that garter snakes have rather large fangs located in the backs of their mouths, and many of the 30-odd species within the genus reach 3 feet or more in length. This means that garter snakes are better-equipped to envenomate a human than some of the other species discussed here.

Nevertheless, garter snake bites rarely produce anything more troubling than a little pain or swelling, and most bites are completely inconsequential.

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