Finding small, round holes scattered across a lawn is a common occurrence. These holes vary greatly in size, ranging from tiny pinpricks to larger, tunneled entrances that displace soil. Identifying the source is the first step toward effective mitigation, as the culprit could be an insect, a foraging mammal, or a mechanical process. Determining if the hole is a temporary foraging mark or a permanent subterranean network helps narrow down the possibilities. The opening’s characteristics—diameter, loose dirt, and depth—provide clues for accurate identification.
Holes Created by Burrowing Insects
Invertebrates often create perfectly round holes that serve as temporary shelters or dedicated nesting sites. These holes are typically small, often measuring less than an inch in diameter, and may feature a distinctive mound of excavated soil at the entrance. Solitary ground bees, which are non-aggressive pollinators, create numerous pencil-sized holes that are usually clean and inconspicuous.
Female cicada killer wasps, some of the largest burrowing insects, excavate a much larger tunnel entrance, commonly measuring about one-half to one and a half inches across. The female forms a characteristic U-shaped spoil pile around the entry point by kicking loose particles out with her hind legs. These tunnels can descend obliquely for six to ten inches, with chambers branching off to house paralyzed cicadas for the developing larvae. Smaller, pinprick holes may indicate the presence of ants or certain species of spiders, which use these tiny openings as access points to their shallow underground networks.
Holes Created by Subterranean Mammals
Larger, more extensive holes are often the work of small subterranean mammals that establish complex tunnel systems beneath the turf. These animals create openings that function as entry and exit points, and the holes are usually one to two inches in diameter. Voles, which are plant-eating rodents, create clean, small entry holes often located near shrubs or under debris where they feed on roots and stems. They also create visible, above-ground runways through the grass, connecting their various small burrows.
Moles, which are insectivores, rarely create a distinct, open hole. Instead, they leave characteristic volcano-shaped mounds of dirt, resulting from pushing deeper tunnel soil to the surface. Their presence is more often marked by raised, soft ridges—the shallow feeding tunnels—rather than a clean entrance hole. Field mice also create small holes, often hidden under leaf litter or woodpiles. Distinguishing between these mammals relies on the type of damage: moles create mounds and raised tunnels, while voles create distinct open holes and visible pathways.
Shallow Marks from Foraging Wildlife
Wildlife damage often consists of shallow, irregular marks rather than deep, round burrows, indicating the animal was digging for a meal. This foraging creates marks that look like divots, scoops, or patches of overturned sod. Skunks, which possess an acute sense of smell, search for white grubs and earthworms, leaving behind numerous conical or circular holes about one and a half to two inches wide.
Raccoons cause more extensive damage, using their dexterous front paws to flip or roll back sections of sod to access subsurface food sources. The resulting damage is often patchy and irregular, with large sections of turf being peeled back rather than a series of neat holes. Birds, such as crows, also forage for grubs and worms, leaving behind small, sharp, shallow poke marks that are distinctly different from the larger holes left by mammals. The irregularity and shallow depth of these marks separate them from permanent burrow entrances.
Identifying Non-Animal Causes
Not all holes in a lawn are the result of biological activity; mechanical or environmental factors can also leave distinct marks. Lawn aeration, a common maintenance practice, creates numerous, uniformly spaced, cylindrical holes. Core aerators remove plugs of soil, typically between 0.5 to 0.75 inches in diameter and two to four inches deep, which are left on the surface to decompose.
These holes are always uniform in pattern and size, easily distinguishing them from the random placements of animal burrows. Other non-living causes include accidental punctures from garden tools, stakes, or temporary structures. A persistent, isolated hole that appears wet or sunken may indicate a leak in an underground irrigation line or a faulty sprinkler head, requiring inspection of the surrounding infrastructure.