Mothballs scattered around the yard are one of the most widely repeated ways to keep snakes away, and they don’t work. Snake experts call the trick an old wives’ tale that won’t go away.1UVA Health. Fact or Fiction: Do Mothballs Keep Snakes Away? The bigger problem is that putting mothballs outdoors is illegal and can harm the people and pets you’re trying to protect.2National Pesticide Information Center. Regulation, Proper Uses, and Alternatives of Mothballs The methods that work don’t make a yard smell bad to snakes. They make it a worse place for a snake to eat and hide.
What Happens When Snakes Meet Mothballs
Most mothballs are almost pure naphthalene or paradichlorobenzene, two strong-smelling chemicals.3PubMed Central. Snake repellent safety and efficacy in Sub-Saharan Africa. What is the evidence? When garter snakes, which are common in US yards, were exposed to naphthalene, sulfur, or both, they did not avoid it.4Great Plains Wildlife Damage Control Workshop Proceedings. The Efficacy of Naphthalene and Sulfur Repellents to Cause Avoidance Behavior in the Plains Garter Snake That held true whether the chemicals were placed in the snake’s own home area or in unfamiliar ground.5Great Plains Wildlife Damage Control Workshop Proceedings. The Efficacy of Naphthalene and Sulfur Repellents to Cause Avoidance Behavior in the Plains Garter Snake The snakes kept moving normally and escaped normally, with no sign of being bothered.6Great Plains Wildlife Damage Control Workshop Proceedings. The Efficacy of Naphthalene and Sulfur Repellents to Cause Avoidance Behavior in the Plains Garter Snake
A snake smells by flicking its tongue and carrying scent particles to an organ in the roof of its mouth.7Canadian Journal of Zoology. Snake tongue-flicking: transfer mechanics to Jacobson’s organ That system is built around trails of prey and mates. A chemical that smells harsh to a human nose isn’t necessarily irritating to that system, because it isn’t a prey or mate cue.
So why does everyone swear by mothballs? A snake often doesn’t come back after mothballs go down simply because snakes move around a lot, and people credit the mothballs for a snake that was only passing through.
Sightings are poor evidence either way. Snakes are secretive and often unseen, so you can’t tell from sightings alone whether anything you did made a difference. A snake found coiled right beside mothballs, though, is direct proof of failure.
Store-Bought Snake Repellents Fall Short Too
Many granular snake repellents use the same naphthalene as mothballs, mixed with sulfur. In a test with venomous vipers, a naphthalene-sulfur formula failed, and most snakes still reached the protected area.8Applied Herpetology. The efficacy of a naphthalene and sulfur formulation to repelthe venomous snake Vipera palaestinae in Israel Garter snakes ignored the same chemicals.9Great Plains Wildlife Damage Control Workshop Proceedings. The Efficacy of Naphthalene and Sulfur Repellents to Cause Avoidance Behavior in the Plains Garter Snake
Essential oils look more promising at first. Some, including cedarwood, cinnamon, and clove, do irritate snakes when sprayed directly on them.10PubMed. Aerosolized essential oils and individual natural product compounds as brown treesnakes repellents Even then, the snakes thrashed around in random directions instead of moving away.11PubMed. Aerosolized essential oils and individual natural product compounds as brown treesnakes repellents When oils were released as a gas or spray into an enclosed space, none drove snakes out reliably.12International Journal of Pest Management. Chemical repellents appear non-useful for eliciting exit of brown tree snakes from cargo Products such as clove oil and some commercial brands repelled some snake species better than others, and results changed with the surface they were applied to.13Scientific Reports. Evaluation of Snake Repellents against the Principal Venomous Snakes of India in Laboratory Condition
Labels deserve a skeptical read. Wording like “may help deter” or “natural” describes hope, not a measured result. Oils and sprays also wash away in rain and weaken in sun, so they need repeated applications, and no repellent creates a barrier a snake cannot cross.
Spraying a snake directly is a bad idea. Irritated snakes thrash in random directions, which can send one toward you. Getting close enough to spray also puts you within striking range of a frightened animal. If a snake is somewhere you don’t want it, give it space to leave or call a professional.
Why Mothballs Outside Are Illegal and Risky
Mothballs are registered pesticides, so following their label directions is required by law.14EDIS. The Facts about Mothballs US labels say mothballs are for indoor use only and are not meant to control snakes or other wildlife.15RHCJC – Reporting What Matters. Do mothballs repel snakes — and is it illegal to use them in your yard? Using them in your yard to repel snakes therefore breaks federal pesticide law.16RHCJC – Reporting What Matters. Do mothballs repel snakes — and is it illegal to use them in your yard? Violations can bring warnings, fines, or other enforcement action.17RHCJC – Reporting What Matters. Do mothballs repel snakes — and is it illegal to use them in your yard? State pesticide regulators warn against using mothballs on snakes even though online tips recommend it.18Clemson News. Do not use mothballs to repel snakes, say state pesticide regulators
People, pets, and wildlife can be harmed by touching mothballs, eating them, or breathing their fumes.19EDIS. The Facts about Mothballs Breathing naphthalene above safe levels can damage the liver, kidneys, lungs, skin, and nervous system.20PubMed Central. Snake repellent safety and efficacy in Sub-Saharan Africa. What is the evidence? Mothballs left outdoors can also contaminate soil, plants, and water.21National Pesticide Information Center. Regulation, Proper Uses, and Alternatives of Mothballs
Yards add their own hazards. Mothballs look like candy or round white pebbles, so small children who play outside may pick them up and put them in their mouths. Dogs may chew or swallow them. Rain dissolves them gradually, carrying the chemical into garden beds, vegetable soil, and possibly groundwater. Placed under a house or in a crawlspace, they can send fumes up into the rooms above.
If a child or pet swallows one, call Poison Control at 1-800-222-1222 or a vet right away, and keep the package to show what chemical it contains. Then gather and bag any mothballs left in the yard.
What Actually Keeps Snakes Away
Snakes go where rodents are, and they follow rodent numbers.22Journal of Applied Ecology. Rodent, snake and raptor use of restored native perennial grasslands is lower than use of unrestored exotic annual grasslands When rodents were reduced, hungry snakes moved around more in search of food and became easier to trap.23The Journal of Wildlife Management. Response of Brown Treesnakes to Reduction of Their Rodent Prey Controlling mice and rats removes the main reason a snake stays. Rodent-proofing means more than traps: it includes sealing food sources and entry points so rodent numbers fall.
Snakes also need sheltered, temperature-friendly spots, so changing vegetation and shade changes where they can live.24Ecological Management & Restoration. Chainsawing for conservation: Ecologically informed tree removal for habitat management Clearing the cover they use makes your yard less suitable. A cleanup covers a few jobs:
- Food: store birdseed and pet food in sealed containers, because spilled seed attracts rodents and rodents attract snakes.
- Woodpiles and rock heaps: move them away from the house, since they shelter both rodents and snakes.
- Grass and shrubs: keep grass short and trim shrubs so branches don’t touch the ground, which removes shaded cover.
- Clutter: clear brush, boards, and junk piles, the hiding places snakes use most.
Sealing the house matters just as much. Walk the outside of the house looking for gaps. A snake can pass through a gap about as wide as its head, so close gaps under doors and around pipes and vents. Screen crawlspace openings and vents with fine mesh so neither snakes nor rodents get in.
Where a snake problem is persistent, a fence can help. Fence material and height both affect whether a snake can climb over.25Global Ecology and Conservation. Barriers for big snakes: Incorporating animal behaviour and morphology into road mortality mitigation design About 1-meter (3-foot) metal mesh fencing with an outward lip at the top stopped climbing ratsnakes in about 93% of attempts.26Global Ecology and Conservation. Barriers for big snakes: Incorporating animal behaviour and morphology into road mortality mitigation design Longer snakes climbed fences more successfully than short ones, though.27Global Ecology and Conservation. Barriers for big snakes: Incorporating animal behaviour and morphology into road mortality mitigation design Installation details count. Bury the bottom few inches so snakes can’t go under, and use small mesh openings, not chain link. Keep plants away from the fence so they don’t act as a ladder.
When a Snake Is Already There
Snakes eat large numbers of rodents.28Animal Conservation. Why Australian farmers should not kill venomous snakes A harmless snake in the yard is doing free pest control, and removing it can raise the number of mice. Most snakes seen in yards would rather escape than bite, and they usually move on within a day or so.
Give the snake space and keep children and pets away. For a snake inside the house or a venomous one, call animal control or a wildlife removal service.
Killing or grabbing a snake tends to backfire. Many bites happen when people try to kill or handle one, because that puts a hand within reach of a frightened animal.
Telling harmless from venomous is harder than it sounds. Learn which venomous species live in your region from a local extension office or wildlife agency, since that is a short list in most areas. Head shape and pupil shape are unreliable on their own, because harmless snakes can flatten their heads and look more dangerous. Treat any snake you can’t identify as potentially dangerous and keep your distance.