No. Mothballs do not keep squirrels away, and they are a lousy idea outdoors. The strong smell of naphthalene or paradichlorobenzene might spook a squirrel for a day or two, but the effect is short-lived, unreliable, and comes with real health and legal problems. I would not waste my money on them.
Mothballs are a regulated pesticide made for sealed containers, not for scattering around a yard or attic. Here is why they fail against squirrels, what they actually do to your family and pets, and what I would use instead.
The Short Version
- They don’t work. A squirrel may avoid the smell for a day or two, then it gets used to it and comes back.
- They are toxic. Naphthalene and paradichlorobenzene can hurt people, pets, and wildlife.
- Using them outdoors is illegal under federal pesticide rules. They are registered as indoor fumigants only.
- Physical barriers and capsaicin sprays actually work and are safe.
Why Mothballs Fail Against Squirrels
The idea sounds reasonable: squirrels have a strong sense of smell, so a powerful odor should drive them off. In practice it falls apart for three reasons.
- Squirrels get used to it. They are cautious around new smells at first, then they learn the odor is not a threat and stop caring. Within a few days they are back.
- The smell dissipates outdoors. Mothball vapor disperses fast in open air, and rain and wind knock the concentration down below anything a squirrel would notice.
- Wrong tool entirely. Mothballs are built to kill moths and other insects in a sealed container by building up toxic gas. They were never meant to repel a large mammal like a squirrel.
Health and Environmental Risks
Scattering mothballs outside exposes your family, pets, and the local wildlife to stuff they should not be breathing or eating.
- Naphthalene poisoning. Breathing the vapors can cause headaches, nausea, dizziness, and a condition where red blood cells get destroyed. Kids and people with a certain enzyme deficiency are especially vulnerable.
- Pet toxicity. A dog or cat that eats a mothball can suffer vomiting, seizures, liver damage, and worse. Cats are especially sensitive to naphthalene.
- Soil and water contamination. Naphthalene can leach into soil and groundwater and stick around for a while, harming beneficial bugs, earthworms, and plants.
- Secondary poisoning. A predator that eats a rodent or insect exposed to mothballs can get the same toxic effects.
Legal Issues With Outdoor Use
Mothballs are registered with the EPA for specific uses only, and the label says sealed containers or storage areas. Using them outdoors, in a garden, or in an attic for squirrel control is:
- Illegal under federal pesticide law. Using a pesticide in a way the label does not allow is a federal violation.
- Fined in many places.
- A neighbor problem if the fumes drift onto someone else’s property, especially in attached housing.
Do not use them indoors for squirrels either. In an attic or crawl space the gas can build up to levels that cause serious breathing problems, and it can seep into your living space through fixtures and wall cavities.
What Actually Works Instead
Here is what I would reach for before a single mothball.
| Method | How it works | Safety | Effectiveness |
|---|---|---|---|
| 1/4 inch hardware cloth | Physical barrier over entry points | Safe | Excellent |
| Capsaicin spray | Strong taste and smell repels mammals | Generally safe when used as directed | Good |
| Motion-activated sprinkler | Sudden water startles them off | Safe | Good |
| Metal tree baffles | Stops them climbing | Safe | Excellent |
| Predator urine | Triggers a natural avoid response | Safe but washes off | Moderate |
| Mothballs (for comparison) | Toxic gas, not made for mammals | Dangerous | Poor |
Home remedies like cayenne pepper, garlic, and peppermint oil get passed around a lot, and they can nudge squirrels for a bit. They are safer than mothballs, but they wash off and need constant re-applying. A barrier is the only fix that lasts.
Frequently Asked Questions
No. And putting them in an attic is dangerous, because the fumes can drift into your living space. Seal the entry points with 1/4 inch hardware cloth instead.
There is no safe or effective amount. The quantity you would need to make a detectable smell in open air would far exceed what is safe for people, pets, and plants. That is one reason they are not registered for outdoor squirrel control.
Mothballs usually contain naphthalene, while moth crystals contain paradichlorobenzene. Both are toxic and both are useless for squirrel control, and neither should be used outdoors or in open areas.
At first, maybe. A squirrel might avoid a treated area for a day or two because the smell is new. Then it gets used to it. If there is food or shelter in the area, the squirrel will ignore the smell and come back.
No. Mothballs in a garden contaminate the soil, kill beneficial bugs and earthworms, and can be taken up by edible plants. Use a capsaicin spray or row covers instead.
Bottom Line
Mothballs are a waste of money for squirrels and a risk you don’t need. They fail because squirrels get used to the smell, using them outdoors is illegal, and the health risks to your family, pets, and the environment are not worth it.
The only fix that holds is physical exclusion with 1/4 inch hardware cloth, metal baffles, and capsaicin sprays. Those are proven, safe, and legal. Skip the mothballs.
