Ground moles are small, burrowing insectivores, not rodents. These subterranean creatures spend nearly their entire lives underground, searching for earthworms, grubs, and other invertebrates that make up their diet. Their continuous tunneling creates extensive networks beneath the surface. This activity leads to the appearance of raised ridges and characteristic mounds of soil, making lethal control methods a common choice for property owners.
Identifying the Pest and Their Tunnels
Effective mole control begins with confirming the presence of a mole, as their damage is often confused with that of voles. Moles create symmetrical, volcano-shaped hills, which are piles of soil pushed up from deep travel tunnels. They also leave shallow, raised ridges or runways across the lawn as they forage just beneath the surface. Vole activity, in contrast, is marked by open, golf-ball-sized holes and distinct, two-inch-wide surface runways, and they damage plants by gnawing on roots and bark.
Lethal control relies on locating an active primary tunnel, which moles use repeatedly. To identify these main arteries, a section of the raised runway can be flattened. If the compressed section is pushed back up within 24 hours, the tunnel is considered active and is an ideal placement site for traps or chemical agents. Tunnels that run straight, often alongside sidewalks or foundations, are more likely to be main travel routes than meandering foraging runs.
Mechanical Trapping Methods
Mechanical trapping is frequently considered the most reliable and environmentally focused method for mole control, as it provides clear confirmation of the kill. Three main designs are commercially available, each working on a spring-loaded mechanism triggered by the mole’s movement. Traps must be set directly into an active, tamped-down tunnel section to ensure the mole interacts with the trigger.
The harpoon or spear trap features a frame that straddles the tunnel, with sharp tines held aloft by a strong spring. The trap is set with a trigger pan resting on the soil surface of the collapsed runway. When the mole attempts to repair or pass through the tunnel, it pushes the trigger upward, instantly driving the tines downward to pierce the animal.
Scissor traps, sometimes called claw traps, use spring-tensioned jaws that are forced closed upon release. These traps are placed directly into a dug-out section of the active tunnel, with the trigger plate positioned to be disturbed by the mole’s movement. The jaws snap shut horizontally, crushing the mole’s body between them.
The third type is the choker or pincer trap, placed entirely inside the tunnel, eliminating visible above-ground components. This design uses a loop or wire cinch mechanism released by the mole pushing against an internal trigger. The loop quickly tightens around the mole’s midsection, providing a clean and immediate kill from a mole traveling in either direction.
Chemical Baits and Poisons
Lethal chemical control relies on ingesting a bait that mimics the mole’s natural diet of earthworms and insects. Since moles are insectivores, traditional rodent baits are ineffective. Modern mole baits are often formulated as synthetic worms or grubs to maximize their appeal and are placed directly into the active tunnel.
Two common active ingredients used in these specialized baits are bromethalin and zinc phosphide. Bromethalin is a neurotoxin that causes swelling of the central nervous system cells, leading to paralysis and death within two to four days. Zinc phosphide is an acute toxicant that reacts with the mole’s stomach acid to produce phosphine gas, which is absorbed through the gut and causes rapid systemic failure.
The use of chemical baits carries a risk of non-target and secondary poisoning to pets and wildlife. Primary poisoning occurs if a pet consumes the bait directly, while secondary poisoning occurs if a predator or scavenger eats a mole that has consumed a toxic dose. Although zinc phosphide does not accumulate in the mole’s tissue, scavengers can be poisoned by consuming undigested bait remaining in the gut. Users must follow label directions precisely to mitigate these risks, including wearing gloves during application and ensuring the bait is deeply concealed in the runway.
Fumigation Techniques and Safety
Fumigation involves introducing toxic gases into the sealed tunnel system to kill the moles by asphyxiation. This method uses commercially available gas cartridges, which are ignited and placed into an active, primary mole tunnel. The cartridges burn slowly, releasing toxic gases, most commonly carbon monoxide, which then spreads through the underground network.
For the technique to be successful, all known tunnel openings and active mounds must be sealed immediately after the cartridge is placed to trap the lethal gas underground. Fumigants are highly toxic, and the fumes are dangerous if inhaled, requiring the use of personal protective equipment, such as gloves and a respirator. Safety regulations strictly prohibit the use of these cartridges near building foundations or utility lines, as the gas could infiltrate occupied spaces or cause an explosion risk.
Fumigation is generally less reliable than trapping because the complex, extensive nature of mole tunnels means the gas may not reach all parts of the system before dissipating. This method should not be confused with dangerous, non-commercial practices, such as mixing household chemicals, which can create extremely toxic and volatile gases. It is also important to check local regulations, as some jurisdictions prohibit the use of certain fumigants for mole control.