Fumigation, often referred to as “gassing,” is a method of mole control that involves introducing a gaseous agent into the mole’s subterranean tunnel network. This technique eliminates mole populations that cause damage to lawns, gardens, and agricultural fields. The process relies on confining a toxic or asphyxiating chemical within the closed environment of the tunnels to ensure efficacy against the target pest. Successfully employing this method requires careful preparation, a clear understanding of the agent being used, and strict adherence to safety and legal mandates.
Mechanism of Fumigation for Mole Control
Mole fumigants generally operate using one of two distinct chemical mechanisms: the release of a highly toxic gas or the production of asphyxiating smoke. The most potent option involves chemical tablets, such as those containing aluminum phosphide, which react with soil moisture to liberate phosphine gas (PH3). Phosphine gas is a potent respiratory toxin that acts by inhibiting cytochrome oxidase, an enzyme necessary for cellular respiration. By blocking this enzyme, the gas prevents the mole’s cells from utilizing oxygen, leading to cellular hypoxia and death within the closed burrow system.
The second common mechanism uses consumer-grade smoke cartridges, typically composed of sulfur, potassium nitrate, and other compounds that combust upon ignition. The burning process generates dense smoke containing lethal concentrations of carbon monoxide (CO) and carbon dioxide (CO2). When confined, this smoke either asphyxiates the mole by displacing breathable air or introduces toxic agents that overcome the animal. The smoke and heat also create an inhospitable environment, which may cause moles to flee the treated area.
Legal Restrictions and Required Safety Protocols
The choice of fumigant is heavily regulated, and users must verify local and state laws, as many effective chemicals are restricted. Highly toxic compounds like aluminum phosphide are classified as Restricted Use Pesticides (RUPs). These materials are not available to the general public and can only be applied by licensed professionals who have undergone specialized training. Professional application often requires a formal Fumigant Management Plan to address potential hazards and ensure safe use.
Even when using legally available consumer-grade smoke cartridges, mandatory safety protocols must be followed to protect human health, pets, and property. Since the combustion process generates significant heat, cartridges must never be used near foundations, dry grass, or other combustible materials due to fire risk. Users should wear appropriate personal protective equipment (PPE), including chemical-resistant gloves and safety glasses, and potentially a respirator if specified. It is imperative to keep children and pets away from the treatment area during and immediately following the application, as the gases pose a serious inhalation hazard.
Preparing and Applying Fumigants
Identifying Active Tunnels
The first step in effective fumigation is accurately identifying the mole’s active tunnels, as treating abandoned runs wastes the product. Freshly excavated, cone-shaped mounds or raised soil ridges are the telltale signs of recent activity. To confirm an active run, collapse a small section of the raised ridge or probe a small hole into the tunnel. If the damaged area is repaired within 12 to 24 hours, the tunnel is currently in use. The main runway, the best placement for the fumigant, is located by probing the ground near the ridge until resistance suddenly disappears.
Application Procedure
Before igniting the fumigant, all other visible openings, exits, and secondary mounds connected to the target tunnel system must be sealed. This ensures the toxic smoke or gas reaches a lethal concentration within the underground network rather than dissipating. To prepare the application site, use a trowel to dig a small opening down to the main tunnel, making the hole just large enough to insert the cartridge. Once the tunnel is prepared, insert and light the fumigant cartridge fuse, ensuring at least two inches protrudes for a minimum five-second burn time. Working quickly, place the lit cartridge fuse-end first into the opening, immediately covering the hole with sod or soil. Care must be taken not to smother the burning cartridge, which would prematurely extinguish the fumigant.
Post-Treatment Monitoring
The final step involves monitoring the area and immediately sealing any small openings that begin to vent smoke, which indicates a breach in the tunnel system. Allowing the fumigant to work undisturbed for several days is necessary. Effectiveness is verified by the absence of new mounds or the repair of the treated tunnel. If new activity appears within a week, the treatment procedure should be repeated in the newly active areas, as a single application is rarely sufficient for the entire burrow system.