Why Do Moles Dig Holes?

Surface Runway Tunnels

• Moles create surface runway tunnels by digging right below the ground to search for food. Some surface runways are used just once while another, known as a main runway, will be used for many years as a main travel lane. Surface runways are usually built along defined human-made borders such as concrete walkways and fencing, as well as along lawn edges and fields.

Deep Tunnels

• Deep tunnels are more permanent. Moles dig these tunnels -- about 6 to 24 inches underground -- to be below the frost of winter and to remain cool during the heat of summer. Deep tunnels are the regular route connecting the nest, rest chambers and the surface runways. Dirt is excavated from deep tunnels and left on the surface in a mole hill that is volcano-shaped.

Nest and Rest Chambers

• Moles also dig tunnels for nesting and to create areas solely for resting. From the deep tunnels, moles make an enlargement about 10 inches below the ground for nest and rest chambers. The chambers are usually in areas offering protection, such as under stone piles, boulders, trees and stumps, bushes and fences. Nests are made from leaves and coarse grasses.

Digging Efficiency

• The mole has large forefeet shaped like paddles with noticeable toenails that allow it to efficiently move through the soil while digging. Surface runways are formed as moles force their way through the soil. When digging deep runs, moles use their bodies to push the soil onto the surface and up through the center of growing mounds that form the volcano-like structures. Deep tunnels are dug at the rate of 12 to 15 feet per hour and surface runways are dug at the rate of approximately a foot per minute. Moles travel through their tunnels at approximately 80 feet per minute.

Benefits

• When moles dig holes, it is beneficial to humans for a number of reasons. Digging runway tunnels creates soil that is aerated and mixed, while feces provide organic matter. Digging deep tunnels allows the organic matter, air and moisture to penetrate well into the deeper layers of soil. As insectivores, moles eat insects that are considered destructive, such as Japanese beetle larvae and cutworms. Only when their digging activity conflicts with human interests, such as in lawns and golf courses, are they considered harmful.