Mole smoke bombs, often sold as gas cartridges or fumigants, are a popular option for homeowners seeking to eliminate destructive mole activity. These products are placed directly into an active tunnel system, where a chemical reaction releases a toxic gas. This article examines the function of these chemical fumigants and evaluates the actual efficacy of this common control method.
How Mole Fumigants Function
Mole fumigant cartridges are self-contained chemical devices intended to generate a lethal gas when ignited. Common over-the-counter varieties contain a mixture of ingredients such as sodium nitrate, sulfur, and charcoal. Once the fuse is lit and the cartridge is placed within the mole tunnel, combustion produces toxic gases like carbon monoxide and sulfur oxides.
The primary goal of this gas is to displace the oxygen within the mole’s subterranean environment, leading to suffocation. A more potent, restricted fumigant, aluminum phosphide, is used by licensed professionals, which reacts with moisture in the soil to release phosphine gas. Both types of gas are meant to travel through the network of tunnels. The effectiveness relies on the gas filling every air pocket and remaining concentrated long enough to be lethal.
Effectiveness and Limitations of Smoke Bombs
Despite the straightforward mechanism, mole smoke bombs are generally considered an unreliable method of control due to the complex nature of the mole’s habitat. A mole’s tunnel system is an extensive, multi-level labyrinth that can cover a large area. The gas from a single cartridge is rarely sufficient to fill this entire volume at a lethal concentration.
The composition of the soil introduces a significant physical limitation, as gas can easily dissipate through porous or sandy earth before reaching the mole. Even when a cartridge is correctly placed in an active tunnel, the mole’s innate behavior works against the fumigant. Moles possess a keen sense of smell and can detect the introduction of the foreign odor and toxic gas.
Upon sensing the change in air quality, the mole will frequently react by rapidly sealing off the affected tunnel segment with soil. This defensive action effectively blocks the gas from spreading further into the main runway system, creating an air pocket where the mole can safely wait out the fumes. If the user incorrectly places the cartridge in a peripheral foraging tunnel rather than a main travel runway, the gas is unlikely to encounter the mole at all. Professional recommendations state that fumigants are not generally recommended because the tunnel systems are too long and porous for reliable results.
Safety and Regulatory Concerns
The use of chemical fumigants introduces several safety concerns for both the user and the surrounding environment. The ignition of gas cartridges presents a fire hazard, particularly if used near combustible materials like dried grass or mulch. Since the mole may push the chemical residue back to the surface, there is a risk of pets or children encountering the unspent material or inhaling residual gas.
Fumigant labels specifically warn against using the product near inhabited structures, tree roots, or any area intended for growing edible plants. Certain highly toxic fumigants, such as aluminum phosphide, are classified as Restricted Use Pesticides and require specific licensing and training for purchase and application. Some local and state jurisdictions have restrictions on the use of these products due to the potential for environmental contamination or harm to non-target wildlife. Always consulting the product label and local regulations is necessary before deploying any chemical control method.
Alternative Control Methods
Since chemical fumigation is consistently ineffective, homeowners should focus on proven, targeted methods for managing mole populations. Trapping remains the most successful and practical approach to eliminate moles causing damage. Effective traps, such as the scissor, harpoon, or choker loop designs, are placed directly into active, primary runways.
Successful trapping relies on the mole’s instinct to clear any obstruction in its main travel tunnel, which triggers the trap. Homeowners can also employ exclusion methods, such as burying hardware cloth or wire mesh vertically into the ground to a depth of 18 to 24 inches to create a physical barrier. While some commercial sonic devices or chemical repellents based on castor oil are available, their efficacy is generally low and inconsistent in permanently deterring moles. Eliminating the mole’s food source, such as grubs, is another strategy, but this is only partially effective because a mole’s diet consists primarily of earthworms, which are beneficial to the soil.