We’re all familiar with honeybees that live in colonies but ground bees prefer the solitary life. They nest in burrows in the ground. Look for a mound of soil standing two inches high, with a quarter-inch hole in the center. Each ground bee female digs her own individual burrow to rear young.
Burrow structure varies according to species, but generally there is a vertical main tunnel with side tunnels branching off from it, each terminating in a single egg cell.
Nesting females attract large numbers of males that fly around the same spot for several days in a mating display. If you look closely you’ll see individual golden-gray bees emerging from the earthen tunnels in your lawn.
Ground bees hatch from the ground in spring and go about their business, pollinating flowers and vegetables. They are not aggressive and rarely sting, even if you stand in the middle of a newly hatched bunch of buzzers.
No control is necessary. If the mounds are objectionable, wash them away with a garden hose.