“Barn snake” isn’t a single species but a common nickname for the non-venomous snakes that show up in barns, sheds, and chicken coops across North America. The two you’re most likely dealing with are the eastern rat snake and the eastern milk snake, both drawn indoors by the same thing: rodents. These snakes are harmless to people and actually provide free pest control, but they can cause problems if you keep poultry or simply don’t want snakes sharing your workspace.
Species You’re Most Likely to Find
The eastern rat snake (Pantherophis alleghaniensis) is the classic barn snake. Adults range from 4 to 6 feet long, with black or dark gray scales and faint lighter markings that become less distinct with age. They’re excellent climbers, capable of scaling rough barn walls and rafters to reach rodent nests. A single rat snake feeds heavily on mice and rats, saving farmers real money on rodent control.
The eastern milk snake (Lampropeltis triangulum) is the other frequent barn visitor. It’s smaller, typically 2 to 3 feet, with smooth scales and a bold pattern of reddish-brown or tan blotches bordered by black on a lighter background. The old myth that milk snakes suckle from cows is exactly that. They’re in the barn for mice, not milk. Milk snakes also eat other small snakes and lizards.
Corn snakes, black racers, and kingsnakes also turn up in agricultural buildings depending on your region. All are non-venomous and rodent hunters.
How to Tell It’s Not Venomous
In most of North America, venomous snakes belong to the pit viper family: copperheads, cottonmouths, and rattlesnakes. A few features separate them from harmless barn snakes, and you can often spot these from a safe distance.
- Head shape. Pit vipers have a wide, triangular head attached to a noticeably narrow neck. Non-venomous snakes have rounder heads that blend more smoothly into the body. One caveat: many harmless snakes flatten their heads when threatened, temporarily mimicking that triangular look.
- Pupil shape. Venomous pit vipers have vertical, cat-like pupils. Harmless species like rat snakes and milk snakes have round pupils.
- Heat-sensing pit. Pit vipers have a small, nostril-like opening between the eye and the actual nostril on each side of the head. No non-venomous snake has this.
- Tail vibration. Rattlesnakes produce a distinctive buzzing rattle, but rat snakes, milk snakes, corn snakes, and racers all vibrate their tails when threatened. In dry leaves, this can sound surprisingly similar to a rattle. Listen carefully and look for the actual rattle segments at the tail tip before assuming you have a rattlesnake.
Young copperheads and cottonmouths also have bright yellow or greenish-yellow tail tips, which can help with identification if you spot a small snake in your barn.
Why Snakes Choose Your Barn
Snakes enter buildings for two reasons: food and shelter. Barns offer both in abundance. Stored grain and animal feed attract mice, and mice attract snakes. Cool, damp spaces between hay bales, under equipment, or inside wall cavities provide ideal hiding spots.
The surrounding environment matters too. Tall grass, wood piles, scrap metal, and debris near the barn give snakes cover as they travel between outdoor habitat and the building. If your barn sits next to overgrown fields or brush piles, you’re essentially rolling out a welcome mat.
Risks to Poultry and Eggs
The biggest conflict between barn snakes and farmers involves chickens. Rat snakes are notorious egg thieves. They can squeeze through gaps as small as an inch, swallow eggs whole, and return night after night. They’ll also take chicks and occasionally small adult birds.
Structurally, the fix is straightforward: cover every opening with quarter-inch hardware cloth. Standard chicken wire has gaps large enough for a determined snake to push through. Check around doors, vents, and where the walls meet the floor or foundation. If a mouse could fit through a hole, so can a snake.
Health Risks to Be Aware Of
Non-venomous barn snakes pose minimal direct danger to people, but they do carry Salmonella bacteria. Snakes can harbor Salmonella without showing any symptoms, shedding the bacteria in their droppings. In a barn where you handle feed, collect eggs, or work around livestock, snake droppings on surfaces can become a transmission route.
Salmonella infection causes stomach cramps, diarrhea, fever, and nausea, typically starting 12 to 72 hours after exposure and lasting several days. It’s especially risky for young children, pregnant women, older adults, and anyone with a weakened immune system. Washing your hands after working in areas where snakes are active is a simple precaution that makes a real difference.
Keeping Snakes Out
The most effective long-term strategy is removing what draws them in. Store all animal feed in sealed containers. Clean up spilled grain and pet food promptly. Keep vegetation mowed short around the barn’s perimeter, and clear away wood piles, old equipment, and debris that provide cover for both rodents and snakes. When the mice leave, the snakes follow.
For physical exclusion, seal every opening one-eighth of an inch or larger. Snakes don’t chew or gnaw their way in, so any sealant or closure that stops a mouse will stop a snake too. Weep vents can be covered with fine mesh screens. If you want a perimeter barrier, a snake-proof fence made of quarter-inch galvanized hardware cloth should stand 36 inches tall, with the bottom edge buried 4 to 6 inches underground and the fence angled outward at about 30 degrees. Gates need to fit tightly and swing inward.
A border of lava rock at least 12 inches wide around the barn’s foundation can also deter snakes. The rough, irregular texture discourages both snakes and the rodents they’re hunting from crossing.
Removing a Snake Safely
If you find a non-venomous snake in your barn and want it gone, the simplest method is guiding it into a pillowcase using a long stick or snake hook, then tying off the open end (well away from where the snake is sitting inside). Transport it to a wooded area or field at least a few hundred yards from your property and release it.
Glue traps designed for snakes are another option for indoor capture. Commercially available boards can be placed along walls where snakes travel. If you want to release the snake alive, check the trap frequently and use vegetable oil to dissolve the adhesive and free the animal. You can also lay damp burlap bags in areas where you’ve spotted snakes. They’re attracted to the cool moisture and will shelter underneath, making them easy to collect.
For venomous species, don’t handle the snake yourself. Place a large bucket or trash bin over it if you can do so safely, weight the lid, and contact your local wildlife agency or a licensed removal service. Most states have regulations about how captured snakes can be relocated or dispatched, so check your local laws before taking action.