Louisiana’s diverse geography, including coastal marshes, pine forests, and swamps, supports over 40 distinct snake species. More than 80% of these species are harmless to humans. Most snakes play a beneficial ecological role, primarily by controlling rodent and insect populations. Learning to recognize the few potentially dangerous species allows residents and visitors to appreciate the state’s natural complexity with confidence.
Identifying Louisiana’s Venomous Species
Louisiana is home to seven native venomous species: pit vipers and the single elapid species. Pit vipers—the Cottonmouth, Copperhead, and three types of Rattlesnakes—possess heat-sensing pits between the eye and nostril. These pit vipers cause the vast majority of venomous snakebites in the state.
The Northern Cottonmouth (Agkistrodon piscivorus), or Water Moccasin, is found statewide near aquatic habitats like swamps and ditches. Adults are heavy-bodied, ranging from dark olive to nearly black, often with a dark stripe through the eye. When threatened, the snake displays the white, cottony interior of its mouth, which gives it its common name.
The Eastern Copperhead (Agkistrodon contortrix) is recognized by its light brown body overlaid with dark, reddish-brown crossbands shaped like an hourglass. These medium-sized snakes are found in forests and woodlands; juveniles have a distinctive bright yellow tail tip. The three rattlesnake species are the Timber Rattlesnake, the Eastern Diamondback Rattlesnake, and the Western Pygmy Rattlesnake.
The Timber Rattlesnake (Crotalus horridus), also known as the Canebrake Rattlesnake, is large, characterized by a black, velvety tail ending in a rattle and dark, chevron-shaped crossbands. They prefer wooded uplands. The Eastern Diamondback Rattlesnake (Crotalus adamanteus) is North America’s largest venomous snake, identified by dark diamonds outlined in light yellow, though it is now rare in Louisiana. The Western Pygmy Rattlesnake (Sistrurus miliarius) is much smaller, typically under two feet long, with a very small rattle that is often difficult to hear.
The only non-pit viper venomous snake is the Eastern Coral Snake (Micrurus fulvius), belonging to the elapid family (which includes cobras). It has a slender body banded with alternating rings of black, yellow, and red. Unlike pit vipers, it uses a fixed-fang system and neurotoxic venom. This species is rarely seen, spending most of its life burrowed underground or beneath leaf litter.
The Common Non-Venomous Snakes
The majority of Louisiana’s snake population is non-venomous and plays a crucial part in the ecosystem. Water snakes (Nerodia genus) are often mistaken for the venomous Cottonmouth. The Diamondback Water Snake (Nerodia rhombifer) and the Banded Water Snake (Nerodia fasciata) are robust, dark-colored aquatic snakes. They will flatten their heads and strike defensively when cornered.
King Snakes (Lampropeltis species), such as the Speckled King Snake, are beneficial because they are immune to pit viper venom and eat other snakes, including rattlesnakes. These snakes are typically black or dark brown with yellow or white speckles or bands.
Rat Snakes (Pantherophis species) are excellent climbers, found in barns and trees where they hunt rodents and birds. The Western Rat Snake, often dark gray or black, can grow quite long, sometimes leading to misidentification. The Eastern Hognose Snake (Heterodon platirhinos) is unique for its upturned snout and dramatic defensive display. This harmless bluff involves flattening its neck like a cobra and feigning death.
Distinguishing Dangerous from Harmless Snakes
Distinguishing venomous from non-venomous snakes relies on key physical characteristics, though observation from a safe distance is always recommended. Most of Louisiana’s venomous species are pit vipers, which generally have a broad, distinctly triangular head. This shape is caused by the presence of venom glands at the back of the jaw.
Non-venomous snakes typically have a more rounded head that is not much wider than the neck. Pit vipers also feature a supraocular scale, an “eyebrow” scale that makes their eyes largely invisible when viewed from above. Non-venomous snakes lack this scale, and their eyes are usually fully visible from an overhead perspective.
For the brightly colored Coral Snake, a simple color pattern rule distinguishes it from the harmless King Snake and Scarlet Snake. The rhyme “Red touches yellow, kills a fellow; red touches black, friend of Jack” describes the banding order. The Coral Snake has red bands bordered by yellow bands, while harmless mimics have red bands bordered by black bands.
Safe Practices for Coexisting with Snakes
The most effective way to avoid snake encounters is to modify the outdoor environment to make it less appealing. Snakes are drawn to areas providing shelter and food. Removing piles of debris, lumber, or rock stacks eliminates potential hiding spots. Keeping lawns closely mowed and storing firewood off the ground removes common sources of cover.
When traversing wooded areas, marshes, or tall grass, wearing thick, over-the-ankle boots and long pants offers protection against accidental bites. Always watch where you step and never place hands or feet into areas you cannot visually inspect, such as dense brush. If a snake is encountered, the safest approach is to leave it alone and give it space to move away.
In the rare event of a suspected venomous snake bite, the immediate priority is to seek professional medical attention by calling 911 or going to the nearest emergency room. While waiting for help, the bitten person should remain calm and still to slow the spread of venom. Rings, watches, or any constricting items should be removed immediately before swelling begins. Do not attempt to suck out the venom, cut the wound, or apply a tourniquet, as these actions cause more harm than good.