The sudden appearance of raised ridges and volcano-shaped mounds across a lawn signals that a mole has established residence. These small, insectivorous mammals spend nearly their entire lives underground searching for food. While they do not eat plants, their extensive tunneling systems can sever plant roots, creating unsightly damage, killing grass, and destabilizing the soil structure. Addressing this problem requires understanding mole behavior and employing targeted control methods.
Identifying the Pest and Its Tunnels
Identifying the specific subterranean pest is the first step toward effective removal, as moles, voles, and gophers create distinct types of damage. Moles are identified by conical or volcano-shaped mounds of fine soil pushed up from deeper tunnels, known as molehills. These mounds rarely feature an open hole because the mole plugs the opening after digging. The other common sign is a raised, spongy ridge across the lawn, which indicates a shallow feeding tunnel just beneath the surface.
These shallow tunnels are temporary foraging routes, but moles also dig deeper, more permanent pathways known as main runways. Pocket gophers, in contrast, create fan-shaped mounds with a plugged hole visible on one side. Voles, which eat plant roots, typically use mole tunnels or create small surface runways, but they do not produce significant soil mounds. To confirm an active runway for trapping, collapse a section of the tunnel by stepping on it, and check the following day to see if the mole has repaired the path.
Active Removal Through Trapping
Trapping is the most effective way to remove moles and is the method professionals rely upon. The goal is to set a mechanical trap directly into an active main runway, which is a deeper, straight tunnel used regularly for travel. These main runways often run parallel to solid structures like sidewalks, fences, or driveways, as moles prefer these protected, stable travel corridors.
Three main types of traps are used: the scissor trap, the harpoon trap, and the choker loop trap. Scissor traps use jaws that close vertically when triggered. Harpoon traps use heavy spikes that impale the mole from above when the trigger pan is disturbed. Choker loop traps are placed inside the runway and use a wire loop that tightens around the mole’s body when activated. Proper placement is paramount; traps should never be set on the loose soil of a molehill or in a shallow feeding tunnel.
Setting the Trap
To set a trap, locate an active, straight section of the main runway by probing the ground until the tool drops into the tunnel cavity. Carefully excavate a small section of the tunnel large enough to accommodate the trap without disturbing the surrounding soil. The trap must be placed so its trigger pan rests directly on the base of the tunnel, ensuring a passing mole will activate the mechanism. After setting the trap, cover the excavated area with loose soil or a piece of sod to block light. Moles avoid an open tunnel and often rush to repair a breach. Always handle traps with caution, engaging the safety catch while setting the device, and follow the manufacturer’s instructions for safe operation.
Repellent and Non-Lethal Deterrents
For homeowners seeking to deter moles without lethal methods, repellents and physical exclusion barriers offer alternatives. Repellent products containing castor oil have shown success in temporarily reducing mole activity in a treated area. Moles find the odor and taste of castor oil offensive, which can make their food sources unappetizing or drive them to tunnel elsewhere.
Applying Castor Oil
To maximize the effect of a castor oil solution, it must be thoroughly watered into the soil profile to reach the depth of the tunnels. A homemade concentrate can be created by mixing six ounces of castor oil with two tablespoons of liquid detergent in one gallon of water. This concentrate is then diluted and sprayed liberally over the affected areas, followed immediately by deep watering to move the repellent downward. Because the repellent breaks down or washes away, repeat applications every few weeks or after heavy rain are necessary to maintain a protective barrier.
Other Deterrents
Other non-lethal methods are less successful, especially those relying on noise or vibration. Devices that emit sonic pulses into the soil are often marketed as deterrents, but research indicates they have little long-term effect on driving moles away.
A more effective exclusion method involves installing physical barriers around high-value areas like flower beds or vegetable gardens. This requires burying half-inch galvanized hardware cloth vertically into the ground to a depth of at least two to three feet. Bending the bottom edge of the wire outward at a 90-degree angle provides an underground apron that prevents moles from tunneling beneath the barrier and entering the protected area.
Long-Term Habitat Modification
Long-term success in managing moles often depends on modifying the yard environment to make it less attractive to these industrious burrowers. Moles primarily feed on invertebrates in the soil, with earthworms making up the largest percentage of their diet, followed by insect larvae like grubs. While eliminating grubs may reduce a secondary food source, it will not completely solve the problem because the earthworm population remains the primary attraction. Homeowners can choose to treat for white grubs, which are beetle larvae, during the period when they are most susceptible to insecticide treatments, typically from mid-June to mid-July. Reducing the overall food supply can encourage moles to move on, but it may also cause them to increase their digging activity as they frantically search for remaining prey before leaving.
Managing soil moisture is another environmental factor that can influence mole presence, as they prefer soft, damp soil where tunneling is easier and prey is closer to the surface. Reducing the intensity and frequency of lawn watering can make the soil drier and less conducive to mole tunneling. In addition to managing moisture, simple cultural practices like regularly rolling the lawn can help collapse shallow tunnels, making the area less habitable. For persistent or widespread infestations that resist homeowner efforts, consulting a professional pest control service is a practical option.