The mole is a small, subterranean insectivore whose presence in a garden often sparks intense debate among property owners. Driven by a constant need to forage, this animal can result in significant landscape disruption. The resulting network of tunnels and mounds forces gardeners to weigh the aesthetic damage against potential ecological benefits. Understanding the mole’s habits reveals that its impact is not purely negative, requiring a homeowner to decide if the disruption outweighs the natural contributions to soil health.
Understanding What Moles Are and How to Identify Their Activity
Moles are specialized insectivores, not rodents, and their diet consists primarily of earthworms, grubs, and other soil-dwelling invertebrates. They do not eat the roots of plants, which distinguishes their activity from common garden pests like voles or gophers. Moles create two types of tunnels: shallow feeding runs that appear as raised ridges on the surface, and deeper, permanent tunnels.
The excavated soil from the deeper tunnels is pushed up, creating the characteristic molehill. These mounds are typically volcano-shaped and symmetrical, with the soil plug centered at the apex. This is a key identifier, as gophers create fan-shaped mounds where the plug of soil is offset to one side.
The Primary Negative Impacts Moles Have on Gardens
The most immediate impact of mole activity is the aesthetic disruption of lawns and turf areas. Their shallow foraging tunnels create unsightly raised ridges, while the molehills leave patches of bare, loose soil scattered across manicured areas. This tunneling activity can cause the grass roots to become disconnected from the soil beneath, leading to brown patches and the wilting or death of turf.
While moles do not consume plant matter, their burrowing still causes significant damage to delicate garden plants and young seedlings. The tunnels they create can sever or dislodge tender roots, which prevents the plant from absorbing necessary water and nutrients. This root disturbance can lead to stunted growth, wilting, and ultimately the death of otherwise healthy plants.
A major indirect consequence of mole presence is that their abandoned tunnel systems provide pathways for other, more destructive pests. Voles, which are herbivores, frequently use mole tunnels to move underground, where they then feast on plant roots, bulbs, and tubers. The mole is often incorrectly blamed for the damage caused by these secondary invaders.
The Ecological Benefits Moles Provide to Soil Health
Despite the damage to turf, constant tunneling activity provides significant ecological benefits, acting as a natural aeration system for the soil. This burrowing loosens compacted earth, which improves the soil structure and enhances water infiltration. This improved drainage and oxygen delivery promote healthier, more robust root growth for surrounding plants.
Moles also play a beneficial role in natural pest control through their appetite. They consume large quantities of soil-dwelling pests, including white grubs and various beetle larvae, which are common pests of lawn and garden roots. A single mole may consume an amount of food equal to 25 to 100 percent of its own body weight daily.
The process of digging brings subsoil up to the surface, assisting in redistributing minerals and organic matter throughout the soil profile. This mixing, known as bioturbation, helps break down organic material and facilitates nutrient cycling. These actions contribute to a more fertile environment and support a diverse and healthy microbial ecosystem beneath the surface.
Managing Mole Activity: Control and Deterrence Methods
For homeowners seeking a non-lethal approach, deterrence methods focus on making the environment unappealing to the mole. Castor oil-based liquid or granular repellents are among the few proven deterrents, as they are thought to irritate the mole’s digestive system and alter the taste of its food sources. These must be applied consistently, especially after heavy rain, to maintain effectiveness.
Physical barriers can be highly effective for protecting specific, high-value garden beds or small areas. Installing underground fencing made of galvanized wire mesh, or hardware cloth, at least 6 to 12 inches deep, can prevent moles from entering a defined space. Habitat modification, such as reducing excessive lawn watering, can also discourage moles by making the soil less hospitable and reducing the populations of their insect prey.
If non-lethal methods fail, trapping is generally considered the most effective method for immediate and targeted removal. Scissor traps and harpoon traps are designed to be placed directly over active, main-run tunnels. Correct placement and proper technique are essential for success, and professional consultation is often recommended to ensure the trap is set in a consistently used pathway.