The common image of a bee colony is a large structure hanging from a tree or housed in a wooden box, like those built by European honeybees. This perception overlooks the reality that the majority of the world’s 20,000 bee species are not social creatures living in massive hives. Most native bee species are solitary and employ diverse nesting strategies that often involve using the earth itself as a home. Many of these pollinators burrow directly into the soil, establishing small, individual nests rather than forming a shared, multi-generational colony.
Which Bees Nest Underground
The vast majority of bees that nest in the ground are solitary species, meaning each female works alone to build and provision her nest. These include groups commonly known as Miner Bees (Andrena species) and Digger Bees. Cellophane Bees (Colletes species) also burrow into the soil, lining their brood cells with a clear, waterproof, polyester-like secretion. Sweat Bees (Halictidae species) are another group of ground-nesting bees that can exhibit a range of social structures, from solitary to primitively social.
These solitary bees do not produce honey or wax and have no stored resources to defend. A single female digs a primary tunnel and constructs multiple individual brood cells, each containing a single egg laid on a ball of nectar and pollen. While solitary, these bees often nest in close proximity, forming large aggregations or “bee neighborhoods” in areas with suitable soil and sun exposure. This clustering can sometimes give the false impression of a large, social colony.
A notable exception is the Bumblebee (Bombus species), which is social and frequently nests underground. Bumblebees typically do not excavate their own burrows; instead, they utilize pre-existing cavities. These cavities are often abandoned nests of small mammals, such as mice or voles, providing an insulated space for the queen to establish her annual, smaller colony. The colony only lasts for one season, with new queens emerging in the fall to overwinter alone.
Anatomy of a Ground Nest
A typical solitary ground bee nest begins with a narrow, cylindrical tunnel excavated vertically into the soil by the female bee. This main entrance burrow usually measures between 1/4 and 1/2 inch in diameter, depending on the species. The depth of the tunnel varies significantly, ranging from a few inches to several feet deep.
From the main shaft, the female bee digs short, lateral tunnels that terminate in small, oval-shaped chambers known as brood cells. Inside each brood cell, she deposits a mixture of pollen and nectar—the “pollen ball”—which serves as the sole food source for the single larva that hatches from the egg. The female seals the cell and repeats the process until her eggs are laid, with the offspring remaining protected underground until they emerge the following year.
The most visible sign of a ground bee nest is the small, conical pile of loose dirt surrounding the entrance hole. This volcano-like mound, technically called a tumulus, is the soil the female bee pushes out as she digs her burrow. These mounds are often temporary, easily washed away by rain or flattened, making ground bee nests challenging to locate unless they are actively being constructed.
Distinguishing Ground Bees from Other Insects
Identifying the insect responsible for holes in the ground is important because many people mistake docile ground bees for aggressive wasps, such as Yellow Jackets. Solitary ground bees are characterized by a fuzzy body, possessing branched, pollen-trapping hairs known as plumose hair, and a plump, stocky silhouette. Their movements near the nest are slow and deliberate, and a single entrance hole will only have one bee entering or exiting at a time.
The behavior of solitary ground bees is non-aggressive; they are not inclined to sting and will only do so if they are actively stepped on or roughly handled. They do not exhibit the defensive behavior that characterizes social insects because they have no colony or food stores to protect. The male bees of these species cannot sting at all, and even the females are considered very docile.
In contrast, Yellow Jackets are social wasps that can be highly aggressive and are often the source of painful ground-nesting encounters. They are physically distinct, featuring a smooth, hairless body, a vivid black and yellow pattern, and a narrow constriction between the thorax and abdomen, often called a “wasp waist.” Their nests are signaled by a continuous stream of multiple workers flying rapidly in and out of a single entrance hole, and they will vigorously defend their nest from perceived threats.
Another common ground-nesting insect is the Cicada Killer Wasp (Sphecius speciosus), a very large, solitary wasp often confused with a bee or hornet. Cicada Killers are not typically aggressive toward humans, but their imposing size can cause concern. They dig their own burrows and provision them with paralyzed cicadas for their offspring.