Controlling subterranean pests often requires lethal intervention, and the most effective method depends entirely on the specific species causing the issue. Understanding the differences between common burrowing pests—moles and voles—is the fundamental step toward successfully eliminating them. Primary methods for lethal control include mechanical traps, toxic chemical baits, and various fumigation techniques.
Identifying the Target: Moles vs. Voles
Moles and voles require different control strategies due to their distinct behaviors and diets. Moles are insectivores, feeding primarily on earthworms, grubs, and other soil-dwelling insects. Voles are herbivores, eating roots, bulbs, seeds, and plant stems. This difference in diet means a bait effective for one will often be ignored by the other.
The damage patterns they leave behind also differ significantly. Moles create characteristic volcano-shaped mounds of soil, which serve as deep-tunnel exits, and shallow, raised ridges that snake across the lawn as they forage. Voles do not create these large mounds; instead, they establish small, dime-sized burrow entrances and above-ground runways. These runways are narrow, clipped-grass trails often visible in the turf, especially under mulch or snow cover.
Mechanical Trapping Techniques
Mechanical trapping is an effective method for eliminating moles and voles without introducing chemicals. Success hinges on placing the trap directly into an active tunnel or runway where the animal is guaranteed to encounter it. To confirm an active mole run, flatten a small section of the raised tunnel; if the tunnel is pushed back up within 24 to 48 hours, it is a primary travel route and a good location for a trap.
Traps designed for moles use a powerful spring mechanism to kill the animal upon contact. Common mole trap designs include the scissor-jaw, the harpoon, and the choker loop traps, all set directly over or into the main subterranean tunnel. The harpoon trap, for example, is set with its trigger pan resting on the flattened section of the tunnel; the mole naturally pushes up on the soil to reopen the run, triggering the lethal downward thrust of the spears. Choker loop traps are inserted into a dug-out portion of the run, designed to constrict the mole as it passes through the tunnel.
For voles, the approach uses common mouse-sized snap traps placed perpendicular to their surface runways or near burrow entrances. The traps are often baited with food appealing to their herbivorous nature, such as peanut butter mixed with oatmeal or a small slice of apple. To increase effectiveness, the traps should be covered with a box or bucket to shield them from non-target animals. Multiple traps are typically required for vole populations, as they often travel in groups along established trails.
Chemical Baits and Toxicants
The effectiveness of lethal baits depends on matching the formulation to the target animal’s diet. Vole baits are generally grain-based pellets or blocks, appealing to their herbivore feeding habits. These products commonly contain active ingredients such as zinc phosphide or anticoagulant compounds, which cause death after ingestion. Zinc phosphide is a fast-acting toxicant that reacts with stomach acids to release phosphine gas, while anticoagulants interfere with the animal’s blood clotting process.
Mole baits must mimic their primary food source, leading to specialized worm-shaped or grub-based products. These baits contain highly concentrated toxicants, often bromethalin, a neurotoxin that causes cerebral edema. Unlike grain-based baits, these worm imitations are designed to be placed directly into the moles’ active underground tunnels to ensure consumption by the insectivore.
The use of any toxic bait introduces a risk of secondary poisoning, where a predator or scavenger, such as a pet or bird of prey, consumes a poisoned mole or vole. Bromethalin is a single-feed neurotoxin with no antidote, posing a significant risk if consumed by non-target animals. Anticoagulant baits can also lead to secondary poisoning. Responsible application requires careful placement deep within the tunnel system or inside secure bait stations to minimize exposure to non-target wildlife and domestic animals.
Fumigation and Gassing Methods
Fumigation involves introducing lethal gases into the subterranean tunnel network. This method requires identifying and sealing all known tunnel entrances to contain the toxic gas within the system. Common gas delivery methods include ignitable sulfur-based smoke cartridges or specialized devices that inject concentrated carbon monoxide (CO) into the runs.
The efficacy of gassing is highly variable and often less successful than trapping, particularly in large or complex tunnel systems where the gas can dissipate through porous soil or undetected exits. Moles are also known to quickly detect the presence of gas and may wall off the affected section of the tunnel, allowing them to escape harm. Fumigation is most effective when the soil is moist, as the water content helps to seal the soil pores, trapping the gas underground. Certain highly restricted fumigants, such as aluminum phosphide, are available only to licensed professionals due to their extreme toxicity and the specialized training required for safe handling and application.