The appearance of unsightly dirt mounds and raised tunnels across a lawn signals the presence of subterranean pests like gophers and moles. These burrowing animals cause significant damage to landscapes and gardens by creating extensive tunnel systems. Fortunately, effective, non-toxic, and natural methods exist to manage these pests. By understanding their specific habits and employing targeted deterrence and exclusion techniques, you can protect your property without harsh chemicals.
Identifying Your Underground Pest
Accurate identification is the first step, as the habits and diet of gophers and moles are distinctly different. Gophers are rodents that primarily feed on plant roots, tubers, and bulbs, posing a direct threat to garden plants. Their mounds are typically fan-shaped, horseshoe-shaped, or crescent-shaped, characterized by a plugged entry hole located off-center. Gophers do not usually leave raised surface tunnels, as their main tunnels are deeper underground.
Moles are insectivores whose diet consists mainly of earthworms, grubs, and other soil invertebrates. Their tunneling activity is driven by hunting for this food source, creating two types of visible signs. The most distinctive sign is the creation of raised ridges or runways on the surface, which feel soft when stepped on. The dirt mounds moles push to the surface are smaller, rounder, and volcano-shaped, with the entry hole often centered within the pile.
Natural Repellents and Exclusion Techniques
Natural repellents introduce strong, unpleasant stimuli into the animals’ environment, encouraging them to relocate without harm. Castor oil is a non-lethal repellent that irritates the digestive system and sense of smell of both moles and gophers. Application involves mixing castor oil with liquid dish soap (as an emulsifier), diluting the concentrate with water, and soaking the active tunnels and surrounding soil. Reapplication is necessary after heavy rainfall or every few weeks to maintain the deterrent effect.
Specific plants can create a natural olfactory barrier in garden areas. Gophers and moles are deterred by plants with strong odors or toxic properties in their roots. Planting these species densely around the perimeter of garden beds helps discourage entry and protects vulnerable crops.
Deterrent Plants
- Gopher purge (Euphorbia lathyris)
- Daffodils (Narcissus)
- Marigolds
- The castor bean plant (Ricinus communis) is highly effective, though its seeds contain ricin and must be planted with caution around children and pets.
For long-term protection, physical exclusion techniques provide an impenetrable barrier against burrowing pests. Galvanized hardware cloth, a rigid wire mesh (typically 1/2-inch or 1/4-inch), is effective when buried. For garden beds, lining the bottom and sides of the planter with this mesh prevents gophers from tunneling up into the roots. For broader lawn or perimeter protection, the mesh should be buried at least 18 inches deep and bent outward at the bottom to discourage digging underneath.
Habitat Modification and Soil Management
Modifying the habitat to make the yard less appealing as a food source provides a lasting solution beyond temporary deterrence. For moles, reducing their primary food source (beetle larvae or grubs) is an effective strategy. This is achieved using biological controls like beneficial nematodes, which are microscopic roundworms that parasitizes and kill grubs in the soil. Heterorhabditis bacteriophora nematodes are highly effective against many common lawn grubs.
Another natural method for grub control is the application of milky spore disease, a naturally occurring bacterium (Paenibacillus popilliae) specific to Japanese beetle larvae. When ingested, the spores multiply, causing a fatal disease and releasing new spores back into the soil for long-term control. This method is highly targeted, posing no threat to non-target organisms like earthworms or pets.
Gophers are attracted to soil conditions that facilitate easy excavation and root foraging, preferring moisture levels between 10% and 20%. Over-irrigating a lawn creates ideal digging conditions. Adjusting watering schedules to allow the soil to dry out more between cycles makes the environment less favorable for gopher activity, as they actively avoid overly wet soil.
The use of sonic or vibration-emitting devices can modify the underground environment. These solar-powered stakes emit pulses into the ground that irritate the sensitive hearing and touch receptors of moles and gophers. While scientific opinion on their long-term effectiveness remains mixed, the constant, low-frequency disturbance encourages burrowing pests to seek quieter territory.
Humane Trapping and Removal
When deterrence methods are insufficient, humane trapping offers a way to physically remove the animal without injury. Specialized live-catch box traps are available for both gophers and moles, designed to capture the animal alive for relocation. The trap must be carefully placed directly into the main, active tunnel run, which is located by gently probing the ground between the mounds.
For gophers, the trap is set in a main runway and triggered when the animal attempts to plug the open tunnel, as they instinctively seal any breach in their system. For moles, tunnel traps are placed perpendicular to the surface runway. Live traps require daily monitoring, and the captured animal must be quickly relocated a significant distance to a suitable, unpopulated area.
A simpler, low-cost removal method involves controlled flooding of the tunnel system. Locating a main tunnel entrance and inserting a hose to flood the burrow forces the animal to the surface. The homeowner must be present to capture the animal immediately upon exit to ensure safe relocation away from the property. This method is most effective when the tunnels are relatively shallow and the soil is not saturated.