Raised ridges and dirt mounds often lead to the assumption that moles eat plant roots. However, moles are insectivores, meaning their diet consists almost entirely of invertebrates. They do not consume plant roots, bulbs, or tubers; plant damage is a side effect of their tunneling, not their feeding habits. The presence of moles is frequently confused with the damage caused by other subterranean pests that are true herbivores.
The Primary Diet of a Mole
Moles are highly specialized mammals adapted for a subterranean life, focused on hunting for protein-rich prey in the soil. Their diet is dominated by invertebrates, with earthworms making up a significant portion of their food intake. They possess a high metabolism that requires them to consume between 70 and 100 percent of their own body weight daily to sustain their constant activity.
Moles patrol their tunnels, which function as traps for prey. Besides earthworms, they consume insect larvae (like beetle grubs and caterpillars), spiders, and centipedes. This appetite drives their continuous burrowing, causing visible disruption in lawns and gardens.
How Mole Tunnels Impact Root Systems
The primary damage caused by moles is a physical separation of the plant’s root system from the surrounding soil. As a mole excavates its extensive network of tunnels, it pushes the soil aside, creating air pockets beneath the turf and around plant roots. These empty spaces prevent the fine root hairs from maintaining contact with the moist soil particles.
This separation leads to desiccation of the roots, starving the plant of water and nutrients. The plant then begins to wilt and die, making it appear as though the roots were gnawed or eaten. Shallow surface tunnels (feeding runs) are disruptive because they lift turfgrass and young plantings entirely out of the ground.
Identifying the Actual Root Eaters
The actual culprits responsible for eating roots, bulbs, and plant material are voles or gophers, both of which are herbivores. Gophers, also called pocket gophers, pull entire plants down into their tunnels to consume the roots and stems. Their mounds are fan-shaped or crescent-shaped, often with the entrance hole plugged and off to one side.
Voles resemble small field mice and eat grass, seeds, bulbs, and the bark of young trees and shrubs, especially in colder months. They often utilize existing mole runways to access plant roots. Vole damage is identifiable by cleanly gnawed roots and bark, or by narrow surface runways clipped through the grass. Distinguishing between the volcanic-shaped mole mounds and the fan-shaped gopher mounds is the first step in identifying the pest causing the damage.