Dime-sized holes, typically measuring between one-half and three-quarters of an inch in diameter, can turn a lawn or garden into a minor mystery. These small openings are rarely a sign of damage and are often evidence of natural activity occurring just beneath the surface. Identifying the creature responsible depends on examining the hole’s structure and the surrounding environment. By observing if the holes are solitary or communal, clean or accompanied by structures, you can determine which common burrowing species is at work.
Solitary Insects and Burrowing Spiders
Many solitary insects and spiders create individual burrows for temporary housing, hunting, or breeding, resulting in a single, distinct hole. Cicada nymphs, which spend years underground feeding on tree roots, create clean exit tunnels roughly one-half inch in diameter when they emerge as adults. These emergence holes are often numerous and are typically found close to trees.
Certain solitary wasps, such as Digger Wasps, also excavate one-quarter to dime-sized holes to provision underground nests for their offspring. The female wasp digs a tunnel, often in sandy or sparsely vegetated soil, where she places paralyzed prey and lays a single egg. Burrowing Wolf Spiders (genus Geolycosa) construct vertical burrows, sometimes lined with silk for stability and protection. These spider burrows may feature a small lip or turret made of silk and debris around the entrance, serving as an ambush point for passing prey.
Social Insect and Wasp Colony Entrances
Holes that serve as entrances to large, organized underground communities often show signs of continuous use and construction. Yellow jackets (Vespula spp.) are the most common social wasps to nest in the ground, typically utilizing an existing cavity like an abandoned rodent burrow. The entrance to their paper nest is usually a single, inconspicuous opening about the size of a nickel or quarter, which may have a small scattering of dirt around it.
Ant colonies also produce dime-sized openings, which are the main access points to their extensive subterranean networks. These holes are commonly characterized by a noticeable, fine-grained mound of excavated soil forming a crater or chimney shape around the entrance. The constant traffic of worker ants moving in and out creates a well-defined opening, unlike the temporary tunnels of solitary insects.
Aquatic and Damp Soil Dwellers
A distinct group of burrowers is tied directly to the presence of water or habitually damp soil, providing a useful geographical clue for identification. Crayfish, sometimes called “land lobsters,” are primary burrowers that create tunnels extending down to the water table to keep their gills moist. As they excavate their tunnels, they roll the mud into small pellets and stack them around the entrance, creating a hollow, cylindrical structure known as a “mud chimney.” These mud chimneys can range in height and often have a dime-sized opening at the top, sometimes plugged with mud to retain humidity during dry periods. The presence of these unique, tower-like structures suggests the activity of burrowing crayfish, particularly in low-lying or poorly drained areas.
Other Damp Soil Burrowers
Another small culprit is the Pine Vole, a rodent that creates dime-sized holes. These holes are often found near the roots of plants in an effort to feed on them.
Differentiating Clues and Context
Accurate identification relies on observing the subtle details surrounding the hole beyond its size. The presence or absence of excavated dirt is an immediate indicator. A clean hole with no displaced soil may point toward a temporary emergence, such as a cicada, or a hole created by soil subsidence from a decomposed root. Conversely, a distinct pile of fine, loose soil around the opening points to an active excavation by an ant colony or a solitary digger wasp.
Observing the traffic at the hole provides further evidence. A constantly busy entrance with numerous insects flying in and out suggests a social colony like yellow jackets or ground-nesting bees. Solitary burrows, such as those made by wolf spiders, will show little activity during the day, with the occupant remaining hidden inside.
The time of year is also a factor. Cicada emergence holes are seasonal, while yellow jacket activity peaks in late summer and early fall as their colonies reach maximum size. Most of these small holes are harmless, and the creatures responsible are often beneficial, with the exception of social wasps, whose proximity to human activity may require professional management.