Do Mothballs Keep Snakes Away? What the Evidence Says

Scattering mothballs around the yard, the foundation, or a shed is one of the oldest pieces of snake advice passed around online and over the fence. It is also one of the most stubborn myths. Mothballs do not reliably keep snakes away, and using them outdoors creates a real hazard to your family, your pets, and the local ecosystem. Here is what the evidence actually shows, and what to do instead.

The short answer: no, they do not work

Mothballs are made of naphthalene or paradichlorobenzene, pesticides designed to slowly release a vapor inside a sealed container of stored clothing. Snakes navigate the world mostly through scent collected by their flicking tongue, so the idea that a strong smell would drive them off sounds plausible. In practice it does not hold up. Snakes routinely move past, over, and even through scattered mothballs to reach the rodents and shelter that drew them in. Wildlife agencies and university extension offices that have looked at home snake repellents, including mothball-based ones, consistently report little to no measurable effect.

Why mothballs are actively dangerous outdoors

This is not a harmless myth to test. Outdoors, mothballs do not stay where you put them. They dissolve in rain, leach into soil and groundwater, and give off fumes at ground level where children, dogs, and cats live and breathe.

• Children and pets mistake them for candy or toys, and naphthalene is poisonous if swallowed.
• The vapor can cause headaches, nausea, and breathing problems for people nearby.
• Runoff harms beneficial wildlife, including the very animals that naturally keep snake numbers down.
• Naphthalene can break down into compounds that linger in soil long after the smell fades.

It is usually against the label, and the law

A pesticide label is a legal document. Mothball labels direct you to use the product in a closed container with stored fabrics, never broadcast across a lawn or poured down a burrow. Applying any pesticide in a way the label does not allow is a violation of federal pesticide law in the United States, and local rules can add penalties on top of that. So beyond simply not working, the mothball trick can put you on the wrong side of the law.

What about the sprays, granules, and ultrasonic gadgets?

If mothballs fail, surely a product sold specifically as snake repellent works? Independent testing says no. Commercial repellent granules, sulfur-and-cinnamon powders, and battery-powered ultrasonic stakes have all been tested by researchers and extension programs, and none has been shown to reliably deter snakes in the real world. Snakes are nearly deaf to airborne sound and do not respond to the vibrations these gadgets produce. Save your money for the things that actually change snake behavior.

What actually keeps snakes away

Snakes show up where there is food and shelter, full stop. Remove those and the snakes move on. None of this involves chemicals.

• Control rodents. Mice and rats are the main meal that draws snakes to a property, so secure pet food, bird seed, and trash, and address any rodent problem first.
• Cut the cover. Keep grass short and clear brush piles, leaf litter, tall weeds, and stacked debris, especially near the house.
• Seal entry points. Close gaps under sheds, decks, porches, and foundations, and screen crawlspace vents and the spaces around pipes.
• Tidy the woodpile. Store firewood off the ground and away from doors and high-traffic areas.
• Reduce standing water and dense ground cover that shelter the frogs and insects some snakes hunt.

For the full playbook, see our guide on how to keep snakes away and the companion piece on what attracts snakes in the first place. If you are seeing snakes regularly, the signs of snakes guide can help you find where they are sheltering.

If a snake is already there

Most snakes in U.S. and Canadian yards are harmless and helpful, and many are excellent at controlling rodents. If you find one, give it room and let it move along. To learn which species actually live near you, use our identification tool and the state and county browser, or browse the species library. If a snake settles somewhere genuinely inconvenient, contact local animal control or a licensed wildlife removal service rather than trying to handle it yourself.

The bottom line: mothballs are a myth that happens to be toxic and often illegal. Skip them entirely. Rodent control, less cover, and sealed gaps are slower, less dramatic, and the only approach that genuinely works.