Groundhogs (woodchucks) are large rodents common in North America. They are powerful diggers that create extensive underground burrow systems, which can cause significant damage to lawns, foundations, and fields. Homeowners often seek simple solutions to deter these pests, leading to the common question of whether mothballs are an effective remedy. The strong, pungent odor of mothballs seems like a natural deterrent, but the science and environmental consequences tell a different story.
The Direct Answer: Do Mothballs Repel Groundhogs?
Mothballs contain either naphthalene or paradichlorobenzene, which are chemicals that turn from solid to gas, creating the product’s characteristic strong odor. This smell is often cited in folklore as a way to repel various wildlife, including groundhogs. Scientific consensus and wildlife professionals confirm that mothballs are ineffective as a long-term groundhog deterrent. A groundhog may show a temporary aversion to the initial strong scent, but the animals quickly adapt to the odor. Their motivation to stay in a secure shelter or near a food source typically overrides any temporary discomfort caused by the chemical smell. Furthermore, the chemicals dissipate rapidly in the open air and soil, meaning the concentration needed to truly annoy a mammal is rarely maintained outside. Attempting to fill an established burrow with mothballs often results in the groundhog simply digging a new entrance or moving to a nearby location rather than abandoning the area entirely.
Safety and Environmental Risks of Naphthalene Use
Using mothballs outdoors is illegal and poses considerable health and environmental hazards. Mothballs are classified by the Environmental Protection Agency (EPA) as registered pesticides intended only for use in sealed containers to control fabric pests. Any use inconsistent with the product label, such as scattering them in a yard or placing them in burrows, is a violation of federal law. The active ingredients, naphthalene and paradichlorobenzene, are highly toxic compounds. Scattering them outdoors risks direct ingestion by children, pets, and non-target wildlife, which can lead to serious medical conditions. When exposed to the elements, these chemicals leach into the soil and can contaminate groundwater.
Understanding Groundhog Behavior and Habitats
The failure of topical repellents is directly related to the complex and robust nature of groundhog burrows. A typical groundhog burrow is an extensive network that can be up to five feet deep and stretch horizontally for 15 to 25 feet beneath the surface. This deep, insulated structure provides a secure, scent-free sanctuary that surface-level chemical fumes cannot penetrate effectively. The burrow system usually includes a main entrance marked by a mound of excavated dirt, along with one to four auxiliary escape routes. Since the burrow serves as a secure home for raising young, a shelter from predators, and a location for winter hibernation, the animal has a high motivation to remain.
Effective and Legal Groundhog Management Strategies
Effective groundhog management relies on physical exclusion and humane removal. The most reliable method is constructing a specialized exclusion fence around the area you wish to protect. The fence should be made of heavy-gauge wire mesh, extending 3 to 4 feet above the ground to prevent climbing. To prevent tunneling underneath, the bottom of the fence must be buried at least 10 to 12 inches deep. The buried section should be bent outward in an “L-footer” design, extending horizontally for another 12 inches. This subterranean flange prevents the groundhog from digging directly down next to the barrier.
Habitat Modification
Modifications to the habitat can discourage new residents by removing attractants. Clearing brush piles, rock stacks, and tall weeds eliminates hiding spots and reduces the appeal of the area.
Humane Trapping and Removal
If a groundhog is already established, humane live-trapping is the most practical solution for removal. Cage traps should be placed near the main burrow entrance and baited with fresh produce. Consult local wildlife regulations, as the legality of relocating or releasing trapped animals varies significantly by state and municipality. Many jurisdictions require the use of a licensed wildlife control operator for removal, as they are equipped to handle the animal responsibly and legally.