A pristine lawn can quickly turn into a frustrating landscape of dirt mounds, sunken tunnels, and scattered holes, indicating an unwelcome invasion. A systematic approach to identification can quickly lead to effective control. Understanding the specific pattern of destruction is the first step toward determining the culprit and addressing the problem efficiently. Restoring your turf involves correctly identifying the animal responsible based on the unique characteristics of the damage it leaves behind.
Analyzing the Damage: Mounds, Tunnels, and Divots
Correct identification begins with a close examination of the physical evidence, classifying the disruption into three main categories. A true hole is an open entrance leading directly into a subterranean network. Mounds are distinct piles of excavated soil pushed up from below or covering a tunnel entrance. Surface runs appear as raised ridges in the turf where the ground has been pushed up but not broken through.
Divots, scrapes, or conical digs are characterized by shallow surface disruption where the turf has been ripped or peeled back. These shallow excavations indicate foraging for food near the soil surface rather than extensive tunneling for shelter. Focusing on the shape, size, and depth of the damage helps narrow down the list of potential pests. The size of the hole or mound is a strong indicator, as smaller pests create smaller disturbances.
The Subsurface Tunnelers: Moles and Gophers
Animals that spend most of their lives underground, like moles and gophers, create the most extensive soil displacement. Moles are insectivores that construct complex tunnel systems in search of earthworms and grubs. Their surface activity is characterized by volcano-shaped molehills, which are symmetrical piles of finely textured soil that rarely contain an open hole in the center.
Moles also create shallow, raised ridges, known as runways, where they tunnel just beneath the surface to hunt. In contrast, gophers are herbivores that feed on plant roots. Gopher mounds are typically horseshoe or crescent-shaped, with a soil plug visible off-center that seals the burrow entrance. The excavated dirt, often chunkier than mole soil, is pushed out to the side of the main tunnel.
The Grub Hunters: Skunks and Raccoons
When the damage appears as widespread, shallow holes, the culprits are likely nocturnal mammals foraging for food. Skunks and raccoons possess an acute sense of smell, allowing them to detect soil-dwelling insect larvae, such as white grubs, just below the turf. They forage primarily during the night, often leaving fresh damage each morning.
Skunks create small, neat, conical holes or shallow divots, typically about the size of a golf ball, as they systematically push their nose into the turf to dig out individual grubs. Raccoon damage is generally more aggressive and messy, often involving larger sections of sod being torn, flipped, or rolled back. The presence of five or more grubs per square foot is enough to attract these predators, even if the turf is not yet showing signs of grub damage.
Smaller Pests and Insect Activity
Lesser-known pests and insects can also create holes, though their damage is usually less extensive than that of larger mammals. Voles, which are small rodents, do not create large mounds. Instead, they leave small, dime-sized, clean, open burrow entrances, often near shrubs or ground cover. These burrows are connected by visible surface runways, which are narrow, above-ground trails where the voles have clipped the grass short.
Another unique signature is the large, perfectly round hole created by the female Cicada Killer Wasp for nesting. This solitary wasp excavates a vertical tunnel approximately half an inch to one and a half inches in diameter, creating a miniature volcano-like mound of coarse soil around the entrance. Finally, earthworms contribute to surface disruption by creating muddy, granular piles of soil known as castings.
Non-Lethal Exclusion and Control Methods
Long-term management focuses on modifying the environment to make it less appealing to pests and using physical barriers. For grub hunters like skunks and raccoons, reducing the food source is the primary strategy. Applying grub control products in late summer can diminish the insect population, making the lawn less attractive for foraging. Perimeter fencing can be effective against skunks, but it must be secured to the ground to prevent digging underneath.
For subsurface tunnelers, physical exclusion is the most reliable method for protecting specific areas. Installing hardware cloth or wire mesh, buried vertically at least 30 inches deep, creates an underground barrier to exclude moles and gophers. Repellents containing castor oil can be applied to the lawn; the resulting odor and taste encourage moles and gophers to relocate. For voles, removing dense vegetation and heavy mulch reduces the protective cover they rely on, forcing them to seek shelter elsewhere.