Subterranean pests can transform a well-maintained garden or lawn into a network of tunnels and damaged plants. Moles and voles are common culprits responsible for this underground destruction. While both creatures live below the surface, their habits and the damage they cause are distinctly different, meaning effective control requires correct identification. This article provides practical strategies for identifying these garden invaders and implementing control methods, from physical barriers to targeted removal techniques.
Understanding the Difference: Moles versus Voles
Successful control begins with accurately determining which animal is causing the damage, as their diets and tunneling habits vary significantly. Moles are insectivores, primarily feeding on earthworms, grubs, and invertebrates found in the soil. Their tunneling activity is a search for food, and they rarely eat plant roots directly, though they can damage them incidentally. Mole damage is characterized by volcano-shaped mounds of soil, or molehills, and raised ridges or shallow tunnels that look like lifted turf.
Voles are true rodents with a herbivorous diet, consuming plant material such as roots, bulbs, stems, and tree bark. They create visible above-ground runways through the grass or mulch, which are narrow, well-worn paths. Their underground burrows have small, open entrance holes, typically the size of a golf ball, that lead to nests and feeding areas. Voles cause direct damage to plants, often causing them to wilt or suddenly fall over due to gnawed roots.
Physical Exclusion Strategies
The most dependable long-term solution for protecting specific garden areas involves the use of physical barriers. Installing an underground fence made of galvanized hardware cloth with a small mesh size, such as one-quarter inch, can effectively block both moles and voles. This material is durable and resists rust, providing a lasting barrier that is difficult for these animals to chew through or bypass.
For maximum effectiveness, the fencing must be buried to a significant depth, ideally between 24 and 30 inches, and should extend a few inches above the soil line to prevent surface entry. Installation involves creating an outward-facing, ninety-degree L-bend at the bottom of the trench before backfilling it with soil. This horizontal flange prevents the pests from burrowing vertically down and under the barrier, redirecting their tunneling attempts away from the protected area.
Individual plants, trees, and vulnerable bulbs can also be protected using wire mesh baskets placed around the root ball during planting. This method is highly effective for high-value ornamentals or vegetables, ensuring that voles cannot access the roots to feed. For raised garden beds, lining the entire bottom and sides with the hardware cloth before adding soil creates an impenetrable barrier from below. Small areas, such as a vegetable patch, can be protected by surrounding them with a trench filled with gravel, as the loose material is difficult for moles to dig through.
Non-Lethal Deterrents and Repellents
When physical barriers are impractical for large areas, non-lethal methods that make the environment undesirable can encourage the pests to relocate. Scent-based repellents are a common approach, particularly those containing castor oil, which is thought to irritate the digestive system of moles and voles. A common homemade mixture involves combining castor oil with liquid dish soap, which acts as an emulsifier, allowing the oil to mix with water for application. This solution is then diluted and applied liberally to the affected areas, tainting the soil and the moles’ food source.
Other scent deterrents include planting specific species that these animals are known to avoid, such as daffodils, alliums, and marigolds, often placed around the perimeter of the garden. However, the effectiveness of these companion planting methods can be highly variable and may not provide complete protection. Some gardeners also deploy solar-powered sonic or vibration devices that are inserted into the ground. These devices emit low-frequency sounds or pulses intended to disrupt the pests’ sensitive hearing and drive them away, but their long-term success is not consistently supported by scientific evidence.
Cultural controls, which modify the habitat to be less attractive, are often the most sustainable deterrents. Moles are attracted to moist soil rich in food, so reducing excessive watering can decrease the availability of earthworms and grubs. For voles, removing heavy ground cover and thick layers of mulch that conceal their surface runways eliminates the protective pathways they use for foraging. Keeping areas around bird feeders clean and removing fallen fruits also reduces readily available food sources that attract voles.
Effective Removal Methods
When exclusion and deterrence efforts fail to resolve the problem, targeted removal becomes necessary, with trapping being the most effective and reliable technique for both pests. For voles, traditional snap-style mouse traps are generally successful, though a high number of traps may be needed due to their rapid reproduction rates. The traps should be placed perpendicular to or directly in the active surface runways and can be baited with items like peanut butter mixed with oatmeal, seeds, or apple slices.
The primary approach for mole removal involves the use of specialized traps, such as the harpoon, scissor, or snare-style models. These traps are designed to be set directly over an active main tunnel. Identifying an active tunnel is the first step, which can be done by collapsing a section of a raised run and observing if the mole repairs it within 12 to 24 hours. Traps must be placed securely into the main runs, often those that run relatively straight or parallel to permanent structures, to intercept the mole as it travels its regular route.
While some may consider using toxic baits that mimic the moles’ natural food source, or attempting to flood or gas the tunnels, these methods have significant drawbacks. Trapping provides immediate confirmation of removal and minimizes the risk of secondary poisoning to pets, wildlife, or scavengers, making it the preferred method for homeowners. It is important to consult local regulations before setting any traps and to handle them with caution to ensure safety.