The Primary Ground-Nesting Bee Species
The species that burrow into the ground fall primarily into three large groups: Miner Bees, Sweat Bees, and certain Bumblebees. Miner Bees (family Andrenidae) are often one of the first bee groups active in early spring, sometimes forming large nesting aggregations in sunny, bare patches of soil. These bees are typically dark-colored and fuzzy, resembling a small honeybee, and are known for pollinating fruit trees and other early-blooming plants.
Another common group is the Sweat Bees (Halictidae), a diverse family that can range in color from black to striking metallic green or copper. While many species are solitary, some Sweat Bees exhibit a semi-social structure where a mother and her daughters may share a tunnel entrance, though each female maintains her own brood cells. These bees earned their common name because they are attracted to perspiration.
The social Bumblebees (Bombus spp.) also nest underground, but they do not dig their own tunnels. Instead, the queen seeks out existing cavities, such as abandoned rodent burrows or sheltered voids near the ground surface. Unlike the solitary species, a bumblebee nest is a true colony that houses workers and is defended by its inhabitants.
Understanding Solitary Nesting Behavior
Most ground-nesting bees use a solitary nesting strategy, meaning each female is responsible for digging her own burrow, provisioning it with food, and laying her own eggs without a worker caste. The female constructs a cylindrical tunnel, often six or more inches deep, and creates individual chambers, or cells, off the main passage.
Each cell is provisioned with a mixture of pollen and nectar, sometimes called “bee bread,” on which she lays a single egg. After sealing the cell, the female repeats this process until her reproductive cycle is complete, with the offspring developing entirely on their own. This digging results in a characteristic small, volcano-shaped mound of excavated dirt at the tunnel entrance.
Although these bees are solitary, they often nest in high-density groupings called aggregations. They choose a site because the soil conditions are ideal for burrowing. The presence of many individual mounds is not an indication of a shared hive structure that will be aggressively defended, as the females are simply individual neighbors utilizing the same patch of dry, sparsely vegetated soil.
Coexistence and Safety in the Yard
Solitary ground-nesting bees are non-aggressive and pose a minimal threat. Unlike social insects that defend a large colony and stored resources, a solitary female has no defensive instinct for the aggregation of nests. A female will only sting if she is accidentally crushed, such as by being stepped on or grabbed.
The males, which are often visible flying low over the nesting site searching for mates, lack a stinger entirely. It is important to distinguish these bees from ground-nesting yellowjackets, which are social wasps that aggressively defend a single, large nest entrance. True ground bees are active for only a short period in the spring, typically three to five weeks, before the adults die off and the next generation develops underground.
If the nesting location is undesirable, the best strategy is non-lethal modification of the soil conditions. Ground-nesting bees seek out dry, warm, and bare soil for easy digging. Increasing the density of the lawn or garden cover, or adding an organic mulch layer, will discourage future nesting. Temporarily increasing lawn watering during the active spring period can also make the soil too damp for them to maintain their burrows, encouraging them to relocate.