Moles are small, subterranean mammals known for their powerful digging ability and sensitive snouts. They are insectivores, not rodents, and primarily consume earthworms, grubs, and other soil invertebrates. Their tunneling activity is driven by a high metabolic rate that requires them to eat large amounts of food. This activity causes damage to lawns and gardens, appearing as raised ridges (shallow feeding tunnels) and volcano-shaped molehills (excavated soil from deeper tunnels). Stopping this disfiguring lawn damage is the primary reason homeowners seek eradication methods.
Identifying Active Tunnels for Treatment
A successful eradication strategy begins with accurately locating the mole’s active tunnel system. Moles create two main types of tunnels: subsurface runways (shallow feeding tunnels) and deep runways (main highways to and from nesting areas). Traps and baits are most effective when placed within these main travel tunnels, which are used daily.
To determine which tunnels are currently in use, collapse a small section of a raised tunnel ridge or cover a molehill with soil. If the mole repairs the collapsed section or disturbs the covering within 12 to 24 hours, the tunnel is considered active and is an ideal placement spot. Focusing on tunnels that run along hard edges, such as sidewalks or foundations, can also be successful, as these obstructions force the mole into a predictable travel path. Moles are most active during the spring and fall when the soil is moist, making these periods optimal for control efforts.
Mechanical Removal: Effective Trapping Techniques
Trapping is the most reliable and environmentally focused method for mole eradication. Success depends on the correct identification of an active main runway and the proper placement of the device. Before setting, handle the traps with gloves to prevent transferring human scent, which can deter the sensitive mole.
Three primary types of lethal traps are used: the harpoon (or spear), the scissors, and the choker (or body grip) trap. The harpoon trap is set above the tunnel and drives spikes downward when the mole pushes up the soil. Scissor traps and choker traps are placed directly into an excavated section of the active tunnel, with the scissor trap snapping shut or the choker tightening a loop around the mole’s body.
For all trap types, a small section of the active runway must be excavated to properly position the device, ensuring alignment with the tunnel path. For traps set below ground, the trigger pan must be level with the tunnel floor, and the surrounding area should be compacted to minimize disturbance. Harpoon traps are generally easier to set, while scissors and choker traps require more precision.
Chemical and Gas Methods: Baiting and Fumigation
Chemical methods offer an alternative lethal approach, primarily through toxic baits and fumigants. Toxic baits are commonly designed to mimic the mole’s natural food source, earthworms, using an active ingredient like bromethalin. Moles are attracted to the bait’s size and texture due to their high metabolism.
These baits must be carefully placed deep within active, underground mole tunnels to minimize the risk of accidental exposure to pets, children, and non-target wildlife. Bromethalin is a neurotoxicant that can be lethal after a single feeding. Label directions must be strictly followed, including keeping pets out of the treated area for at least two weeks.
Fumigants, such as gas cartridges, are also used to introduce toxic gas into the tunnel system. However, the efficacy of fumigants is inconsistent, as moles can quickly seal off sections of their tunnels, blocking the toxic gas before a lethal concentration is reached. Gas can also escape through the complex network of shallow tunnels or porous soil, reducing effectiveness. Some professional-grade fumigants, such as those that produce phosphine gas, are restricted-use pesticides and should only be applied by certified professionals.
Non-Lethal Management and Exclusion
For those preferring a humane approach, non-lethal management focuses on deterrence and physical exclusion. Repellents often use castor oil, applied as a liquid spray or in granular form. The castor oil works by either coating the mole’s food source, making it unappetizing, or by causing digestive discomfort, encouraging the mole to leave the area.
Liquid repellents require frequent reapplication, especially after heavy rain or watering, as the active ingredient can wash away. Sonic or vibration devices are also marketed as mole deterrents, though their success is inconsistent due to the mole’s ability to tunnel around the localized disturbance.
The most definitive non-lethal solution is exclusion, which involves installing physical barriers. This is accomplished by burying galvanized wire mesh or hardware cloth vertically around garden beds or property perimeters. The barrier must extend to a depth of at least 18 to 24 inches. A portion of the mesh should also be bent outward at the bottom to form a small “L” shape, which prevents the mole from digging directly underneath. While labor-intensive, this method provides a permanent block against entry into a protected area.