Moles are small, subterranean mammals whose diet consists almost entirely of earthworms, grubs, and other soil-dwelling invertebrates. Their presence is usually first noticed through the unsightly damage they inflict on lawns and gardens. While their primary habitat is the yard, their extensive tunneling systems can extend near or underneath a home’s foundation, basement, or crawl space. This disruption of soil structure can lead to indirect issues like water pooling. Addressing a mole infestation is important because their constant digging represents a potential structural nuisance near the house perimeter.
Confirming the Intruder
Successfully managing a pest problem requires accurate identification, as mole activity is often confused with that of voles or gophers. Moles create characteristic damage, including raised, surface-level ridges that serve as feeding runways. They also produce volcano-shaped mounds of fine, loose soil, called molehills, which result from excavating deeper tunnels. Moles are insectivores whose diet is mainly earthworms; they will not consume plant roots, though their tunneling can inadvertently sever them.
Voles are rodents that primarily eat plants, seeds, and bark, leaving behind small, open burrow holes instead of large mounds. Vole damage is characterized by visible, shallow surface runways of clipped grass, which moles do not create. Since moles are insectivores, they are not affected by common rodent baits made from seeds or grains. Correct identification is necessary for choosing an effective control method, as treating for the wrong animal will allow the mole problem to worsen.
Exclusion and Deterrence Methods
Non-lethal methods focusing on exclusion and deterrence are the first line of defense against moles near the house structure. Installing a physical barrier around the foundation or garden beds is the most reliable way to prevent tunneling into vulnerable areas like crawl spaces. This involves trenching a perimeter about 12 inches deep and lining it with galvanized hardware cloth or wire mesh. The mesh must extend below ground and a few inches above the soil line, physically blocking the mole’s path while allowing water to drain.
Deterrent products containing castor oil can be applied to the soil to make the mole’s food source unappealing. Castor oil acts as a repellent, causing temporary digestive upset and driving moles to seek food elsewhere. Electronic devices that emit ultrasonic pulses or vibrations have not been scientifically proven to be effective. Reducing excess soil moisture also helps, as wet soil attracts earthworms and grubs, which are the mole’s primary food source, closer to the surface.
Active Removal Strategies
When exclusion methods are insufficient, active removal is necessary, with trapping being the most consistently effective strategy for moles. Trapping requires identifying an active tunnel by collapsing a section of a surface run; if the mole pushes the soil back up within 24 hours, the tunnel is active and suitable for trap placement. The three most common types of lethal traps are the harpoon, the scissor, and the loop or choker trap.
The harpoon trap is often considered the easiest for homeowners to set, placed directly over the collapsed section of the active runway. Scissor traps and loop traps, such as the “Out-of-Sight” design, are set directly into an excavated portion of the tunnel. It is crucial to ensure the trap is set firmly, and any openings created during placement are sealed with soil. Moles will avoid tunnels they perceive as damaged or exposed, so preventing light or air from entering is necessary.
Mole-specific baits are also available, formulated to resemble natural food like earthworms, and often contain a neurotoxin such as bromethalin. These baits must be placed directly into the active, underground tunnel system to reduce the risk of non-target animals ingesting them. Bromethalin is highly toxic to dogs and cats, and there is no antidote, necessitating extreme caution and strict adherence to label instructions for underground placement. Zinc phosphide is another bait option, but it also presents a risk of primary and secondary poisoning to pets and wildlife.
Securing the Perimeter Long-Term
Once the active mole is removed, a long-term strategy is required to discourage new moles from colonizing the area. First, repair the physical damage by collapsing all remaining surface tunnels and leveling the soil mounds. Any entry points or damage to the foundation, such as gaps in walls created by tunneling, must be immediately sealed with concrete or heavy-gauge wire mesh. Sealing these areas denies future access and prevents water intrusion or exploitation by other pests.
Long-term maintenance should address the soil conditions that attract the mole’s food sources. While moles prefer earthworms, they also consume grubs, and a grub-infested lawn is a strong attractant. Applying a preventative grub control product will reduce this food source, though it will not eliminate moles entirely. Maintaining a healthy, well-draining lawn that limits excessive moisture makes the area less appealing for moles seeking an easy food supply and stable habitat.