Squirrels can quickly become a nuisance, causing damage by gnawing on wires, digging up gardens, and establishing nests in quiet spaces like attics. Many homeowners search for a quick solution, often encountering the popular belief that the strong odor of mothballs will drive the pests away. This article provides the definitive answer, examining the chemical reality and the regulatory status of using this product against wildlife.
The Definitive Answer: Do Mothballs Deter Squirrels?
Mothballs are overwhelmingly ineffective and unreliable for deterring squirrels in open or semi-open environments. They are solid fumigants designed for use in sealed spaces, containing active ingredients like naphthalene or paradichlorobenzene. These compounds slowly transition from a solid state directly into a toxic gas through a process called sublimation.
The product is intended to kill insect pests, such as clothes moths and their larvae, by concentrating the toxic vapor within an airtight container. When mothballs are placed outdoors, the volatile chemicals dissipate rapidly. The vapor concentration never reaches a level high enough to be a meaningful deterrent to a mammal like a squirrel.
While the initial pungent smell may cause a brief pause, squirrels are highly adaptable and quickly become habituated to the odor. Their motivation to access a safe nesting site or a consistent food source easily outweighs the annoyance of a low concentration of the chemical vapor. Using mothballs in this manner is not only wasteful but also fails to provide any lasting solution to a persistent squirrel problem.
Toxicity and Regulatory Status
Using mothballs to repel squirrels constitutes a misuse of a registered pesticide, carrying significant health and legal hazards. The chemicals are classified as pesticides by the Environmental Protection Agency (EPA). The legally binding product label strictly limits their use to killing specific fabric pests inside tightly sealed containers.
Scattering mothballs in a yard, garden, or attic is considered an illegal, off-label use of the pesticide. This misuse can lead to the chemicals contaminating soil and groundwater, posing an environmental risk. Furthermore, the toxic fumes can seep into living spaces, causing respiratory irritation, headaches, or more serious issues, especially for children and infants.
The mothballs themselves present a direct toxicity risk to squirrels and domestic pets who might mistake the small white balls for food. Ingestion of the active ingredients, particularly naphthalene, can lead to severe health consequences in pets, including vomiting, lethargy, and the destruction of red blood cells, a condition known as hemolytic anemia. Due to these serious health and environmental risks, the EPA advises against using mothballs as a general wildlife repellent.
Effective and Approved Alternatives
Since mothballs are neither effective nor legal for squirrel control, homeowners must focus on approved, practical alternatives. The most successful long-term strategy is exclusion, which involves physically preventing squirrels from entering a home’s structure. All potential entry points into attics, crawlspaces, and sheds, including unsealed soffits, vents, and chimney gaps, should be sealed with heavy-duty materials.
Hardware cloth, a galvanized wire mesh with openings no larger than one-half inch, is highly effective for covering vents and vulnerable openings. Chimneys should be fitted with professional-grade metal caps to block access while still allowing proper ventilation. This physical barrier approach addresses the root cause of the problem by eliminating nesting opportunities.
Habitat modification is another important strategy that reduces the attractants drawing squirrels to a property. Securing all outdoor garbage cans with locking lids and removing standing water sources can make a yard less appealing. Bird feeders should be modified with specialized baffles or switched to safflower seeds, which birds enjoy but squirrels find bitter.
Approved repellents can offer temporary relief but require consistent reapplication. Taste-aversion products containing capsaicin, the compound that gives chili peppers their heat, are registered for use against squirrels. When applied to bulbs, plants, or surfaces, these repellents create a harmless, bad taste that discourages chewing and digging, providing a safe, legal, and effective method for managing squirrel presence.