The appearance of unexpected holes and tunnels across a lawn is a common problem for homeowners. Addressing this issue effectively requires a methodical approach that moves beyond temporary fixes. Successful remediation hinges on first correctly identifying the culprit, understanding its motivation for digging, and then implementing a multi-layered strategy of habitat modification, exclusion, and non-lethal deterrence. Pinpointing the source of the damage allows for the selection of targeted control methods, which are more effective than general treatments.
Pinpointing the Animal Responsible
Correctly identifying the animal causing the damage is the first step in eliminating the problem. The size, shape, and location of the excavation provide clear diagnostic clues to distinguish between common yard diggers.
Moles create volcano-shaped mounds of fine soil (molehills) and raised surface ridges marking their shallow feeding tunnels. These insectivores seek earthworms and grubs, not plants, and rarely leave an open hole visible in the mound center. Voles, which are herbivores, do not produce mounds but leave small, pencil-sized holes, often found near plant bases or under ground cover. Vole activity is characterized by a network of narrow, flattened surface runways connecting these small entry points.
Skunks and raccoons are nocturnal foragers that dig shallow, cone-shaped depressions or divots, typically one to three inches deep, while searching for subterranean insects like grubs. This rooting damage often appears overnight and looks like small patches of disturbed turf. Squirrels and chipmunks create small, neat holes, about the diameter of a quarter, used to bury or retrieve nuts and seeds. These holes are usually covered quickly, making them less disruptive than extensive tunneling. Larger, more destructive holes near foundations or under structures may indicate domestic pets or larger burrowers like armadillos or groundhogs.
Eliminating the Primary Attractants
Once the animal is identified, the next step is to remove the environmental factors drawing the pest to the property. This involves eliminating food sources and reducing available shelter to make the yard less appealing.
Targeting the subterranean insect population is necessary when the damage is shallow foraging holes, typical of skunks and raccoons. Homeowners can apply biological controls, such as beneficial nematodes, which infect and kill grub larvae within the soil. Milky spore is another biological option, effective primarily against Japanese beetle grubs, which establishes in the soil over time for long-term control.
Chemical treatments are also available. Preventative applications containing chlorantraniliprole or imidacloprid are applied in early summer to target newly hatched grubs. Curative treatments, containing carbaryl or trichlorfon, are applied in late summer or fall when grubs are actively feeding. All chemical applications must be immediately watered into the soil to reach the root zone. Beyond insects, securing all potential food sources is important, such as consistently bringing pet food bowls inside at night. Reducing harborages involves removing debris piles, old lumber, and brush that provide animals with shelter.
Physical Barriers and Exclusion Techniques
Physical exclusion methods rely on durable materials to create permanent, impenetrable barriers against persistent digging. These techniques prevent animals from accessing vulnerable areas like gardens and foundations.
The “L-foot” exclusion technique is effective for preventing animals from digging under perimeter fences. This involves burying heavy-gauge wire mesh, such as galvanized hardware cloth with one-inch openings, 12 to 18 inches deep. The bottom edge of the mesh is then bent outward at a 90-degree angle, extending horizontally underground for at least 12 inches away from the fence line. When a digging animal encounters this horizontal apron, its instinct to dig deeper is thwarted, and it abandons the attempt.
For localized surface foraging, a layer of hardware cloth can be laid horizontally just beneath new sod or garden beds, preventing the animal from breaking the soil surface. Securing access points under structures like sheds and decks is achieved by attaching the same wire mesh to the base. The mesh should be buried vertically 12 to 18 inches deep and bent into the L-foot configuration, preventing burrowing animals like skunks or groundhogs from denning there.
Non-Lethal Deterrents and Repellents
When physical barriers are impractical, non-lethal deterrents use sensory input to discourage animals from entering an area or continuing to dig. These methods rely on frightening the animal or making the environment taste or smell offensive.
Taste and scent repellents typically use active ingredients that are unpleasant but harmless to the animal. For burrowing animals like moles, repellents containing castor oil are common, as the oil permeates the soil and makes their food sources unpalatable. Commercial sprays often contain putrescent egg solids, which mimic the scent of decay, or capsaicin, a chili pepper compound that provides a taste irritant. Repellents must be reapplied frequently, especially after heavy rain, to maintain effectiveness.
Motion-activated devices offer a humane, non-chemical solution for broader deterrence. Motion-activated sprinklers use an infrared sensor to detect an animal, triggering a sudden burst of water and a startling noise. This combination conditions the animal to avoid the protected area over time, working effectively against species like raccoons, deer, and skunks. Before employing any control method, homeowners should check local municipal or state wildlife regulations, as rules regarding the handling of nuisance wildlife vary significantly by jurisdiction.