Digger bees build their nests underground, excavating tunnels and brood chambers in bare or sparsely vegetated soil. Most nest cells sit between 6 and 16 inches below the surface, though some tunnels in reused nests can extend dozens of feet deep. If you’ve noticed small mounds of dirt with holes in your yard, you’re likely looking at a digger bee nesting site, and understanding what’s going on below the surface can help you decide whether to leave them alone or gently encourage them to move on.
What a Digger Bee Nest Looks Like
From the surface, a digger bee nest appears as a small mound of excavated soil with an entrance hole in the center, roughly the diameter of a pencil. Some species in the genus Anthophora build distinctive turrets at their nest entrances, tiny chimney-like structures made of clay that rise above the soil. One species, Anthophora abrupta, is actually nicknamed the “chimney bee” because of these turrets. When many females nest near each other, you may see dozens or even hundreds of these little mounds clustered together across a patch of bare ground.
Below the surface, each tunnel branches into a network leading to individual brood chambers. These are small sealed cells where the female deposits a mixture of pollen and nectar, lays a single egg, and moves on to build the next one. The architecture is simple but effective: each cell is a self-contained nursery stocked with everything a developing bee needs.
How Digger Bees Choose a Nesting Site
Digger bees are picky about where they dig. Research published in the Journal of Pollination Ecology measured nine different soil properties at nesting sites and found that two factors stood out: soil stoniness and soil temperature at 10 centimeters deep were both positively associated with bee numbers, while heavy vegetation cover and high water drainage rates were negatively associated. In practical terms, digger bees prefer warm, well-drained soil with some grit to it, and they avoid areas with thick plant cover.
This explains why nests commonly appear in south-facing slopes, garden edges, patchy lawns, and compacted dirt paths. Clay soils are especially popular with Anthophora species, which have been found nesting in clay banks, cob structures, and even clay pizza ovens. If your yard has a sunny spot with thin grass and exposed soil, it’s prime real estate for digger bees.
Solitary Bees That Nest in Crowds
Despite appearances, digger bees are solitary. There’s no queen, no worker caste, and no shared hive. Each female digs her own tunnel, provisions her own brood cells, and seals them up before she dies, never meeting her offspring. The underground tunnels in an aggregation are not connected to each other.
That said, digger bees often nest in dense aggregations because good nesting habitat attracts many individuals to the same patch of ground. Some species take this a step further with communal nesting, where multiple females share a single entrance tunnel but each maintains her own separate brood chambers inside. This is less like a colony and more like an apartment building: shared front door, private units.
The term “digger bee” is broad and covers many species. Miner bees, certain sweat bees, and other ground-nesting species all fall under the umbrella. Most belong to the genus Anthophora within the family Apidae, but the label is informal. There’s even one oddball, Anthophora terminalis, that nests in pithy stems and decaying wood instead of soil, lining its chambers with plant oils.
How to Tell Them Apart From Yellowjackets
Ground-nesting bees are frequently mistaken for yellowjackets, and the distinction matters because the two require very different responses. Digger bee aggregations have many individual entrance holes, each surrounded by its own small mound of excavated soil. Yellowjacket colonies funnel through a single entrance hole with heavy traffic, guard bees patrolling nearby, and no visible soil turrets.
Behavior is another giveaway. Male digger bees hover around the nest area and may fly toward you, which looks intimidating but is entirely harmless. Males have no stinger at all. Females do have stingers but are not aggressive. They sting only when physically handled or pinned against skin. Yellowjackets, by contrast, will actively defend their nest from a distance and sting repeatedly. If you can stand a few feet from the holes and watch bees calmly coming and going without any buzzing toward you, you’re almost certainly looking at digger bees.
Why the Nests Are Worth Keeping
Digger bees are efficient pollinators of wildflowers, fruit trees, and garden crops. Because each female provisions her own brood cells, she visits far more flowers per individual than a honeybee worker following colony instructions. Their nesting activity also aerates compacted soil, improving water infiltration and root growth. A digger bee aggregation in your yard is a sign of a healthy local ecosystem, and the bees are typically active for only four to six weeks in spring before the adults die and the nest area goes quiet until the following year.
Managing Nests in Your Yard
If you’d rather not share your lawn with digger bees, the most effective approach is changing the habitat so it no longer appeals to them. The University of Maryland Extension recommends heavy watering with a lawn sprinkler, which discourages nesting because digger bees need relatively dry soil for stable tunnels. Running a sprinkler over the nesting area for extended periods during their active season can push them to relocate.
For a longer-term solution, eliminate the bare ground that attracted them in the first place. Establishing dense turf grass over the area removes their preferred nesting substrate. If the spot won’t support a healthy lawn (too shady, too compacted, or too sloped), thick groundcover plantings or a heavy layer of mulch will also deter nesting. Both strategies work by increasing vegetation cover and reducing the warm, exposed soil conditions digger bees seek out.
Pesticides are unnecessary and counterproductive. The bees pose virtually no sting risk, their nests don’t damage turf roots or structures, and killing them removes pollinators your garden depends on. If you can tolerate them for the few weeks they’re active, the simplest approach is to do nothing and let them finish their brief season.