The presence of squirrels often leads homeowners to search for quick solutions to deter the unwelcome guests. Many people turn to mothballs as a convenient, strong-smelling repellent, believing the pungent fumes will drive the animals away. This common assumption warrants a closer look to determine both the effectiveness and the safety of this method. This article investigates the use of mothballs for squirrel control and outlines the associated legal and health considerations.
The Composition and Approved Use of Mothballs
Mothballs are solid pesticides containing high concentrations of either naphthalene or paradichlorobenzene (1,4-dichlorobenzene). These chemicals slowly transform from a solid into a toxic gas through sublimation. The continuous release of this gas makes mothballs effective against their intended target pests.
The Environmental Protection Agency (EPA) registers mothballs specifically as insecticides to control clothes moths and other fabric pests. The official product label directs that they must only be used inside tightly closed, airtight containers. This sealed environment allows the toxic vapors to accumulate to a lethal concentration, ensuring the chemical remains contained while killing the insects.
Evaluating the Effectiveness Against Squirrels
The idea that mothballs repel squirrels is based on the animal’s sensitive sense of smell and the mothball’s strong odor. While the initial, intense smell may cause a temporary startle, it is rarely a long-term solution. Squirrels are highly motivated by the need for food, water, and secure nesting sites, instincts that an unpleasant odor often fails to override.
Scientific evidence supporting the long-term efficacy of mothballs against mammals is scarce and unconvincing. In open areas like attics or gardens, the chemical vapors dissipate quickly, failing to reach a concentration high enough to be a true fumigant. Squirrels quickly become accustomed to the smell, sometimes moving the mothballs aside if they are placed near a desired food source. Ultimately, mothballs are unreliable and ineffective for sustained deterrence.
Health and Environmental Risks of Outdoor Application
Using mothballs outside of a sealed container, such as scattering them in a yard or attic, creates significant health and environmental hazards. Both naphthalene and paradichlorobenzene are toxic chemicals that pose a risk to humans, pets, and non-target wildlife. When placed outdoors, the chemicals contaminate the soil, and rainwater runoff can carry the toxins into groundwater supplies and aquatic ecosystems.
Children and pets are at particularly high risk because the small, white balls can be mistaken for treats and accidentally ingested. Ingestion of even a single mothball can lead to severe medical issues, including vomiting, abdominal pain, and acute hemolytic anemia. Furthermore, inhaling the fumes in an unventilated area can cause headaches, nausea, eye irritation, and potential liver and kidney damage.
Regulatory Status of Mothballs as Pest Control
Mothballs are classified as registered pesticides, meaning their use is strictly regulated by the Environmental Protection Agency (EPA) under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). The product label is a legally binding document that specifies the exact pests and locations for which the chemical is approved. The label only authorizes their use for controlling fabric pests in sealed containers.
Using mothballs for any purpose not listed on the label, such as attempting to repel squirrels, is known as “off-label use” and is a violation of federal law. The labels do not list squirrels, rodents, or other wildlife as target pests. Misusing a pesticide in this way can result in fines and liability, particularly if it leads to environmental contamination or health issues.
Non-Chemical Methods for Squirrel Deterrence
The most effective and safest approach to managing squirrel conflicts involves exclusion and habitat modification. Exclusion focuses on physically blocking access to areas where squirrels are causing problems, such as sealing gaps around vents, chimneys, and rooflines. Homeowners should use durable materials like heavy-gauge wire mesh or metal hardware cloth, as squirrels can easily chew through weaker barriers.
Exclusion and Habitat Modification
Habitat modification involves removing or securing attractants that draw squirrels to the property. This includes securing outdoor garbage bins, removing fallen fruit, and using squirrel-proof bird feeders. For a repellent approach, commercially available capsaicin-based sprays or physical deterrents like motion-activated sprinklers offer an approved, non-toxic alternative.