Many people commonly associate bees with large, communal hives, yet a significant portion of bee species leads a different kind of life. These fascinating insects, known as ground-nesting bees, often make their homes directly in the soil of lawns and gardens. While their presence might initially cause concern, these bees are generally docile and pose little threat to humans or pets. Understanding their habits helps appreciate their role in local ecosystems.
Identifying Ground Burrows
Spotting a ground bee burrow involves looking for specific characteristics. Ground bee nests usually appear as small, perfectly round holes, about ¼ inch wide, often surrounded by a miniature volcano-shaped mound of excavated soil. This mound is formed from soil the female bee removes while constructing her tunnel.
Activity around these holes, such as bees flying in and out, is most apparent in early spring or summer. These differ from yellow jacket nests, which have larger entrances (over an inch wide) and constant streams of multiple insects, indicating a social colony. Ground bee holes are typically used by a single bee at a time.
Common Types of Ground-Nesting Bees
Several types of ground-nesting bee species are commonly encountered. Miner bees (Andrena) are among the earliest to emerge in spring, typically dark-colored with banding, ranging from ⅜ to ¾ inch. They often have pale hairs along their inner eye edges.
Digger bees (Anthophora, Habropoda) are robust, fast-flying bees with velvety fur, 4 to 16 millimeters. Some Anthophora species form turrets at nest entrances. Sweat bees (Halictidae) are another common group, often small (¼ to ¾ inch) with dull or metallic coloration, including greens, blues, or purples. While many ground-nesting bees are solitary, meaning each female builds her own nest, they may nest in close proximity, creating the appearance of a colony.
Why Bees Burrow
Ground-nesting bees burrow to create a secure environment for their offspring. The female bee is solely responsible for constructing and provisioning her nest. She excavates a main tunnel, branching into side tunnels, each ending in a brood cell. Each cell is provisioned with a ball of pollen and nectar, serving as a food source for the developing young.
A single egg is laid on this food ball, and the cell is sealed, sometimes with a waterproof lining. Larvae feed on these provisions, developing into pupae and then into adults, often overwintering in the nest to emerge the following spring. These bees prefer nesting in well-drained, bare, or sparsely vegetated soil, as these conditions are ideal for burrowing and protecting their young.
Coexisting with Ground-Nesting Bees
Ground-nesting bees are non-aggressive and rarely sting unless provoked or handled roughly. Males, often seen flying around nest entrances, lack stingers and are harmless. These bees are beneficial pollinators, contributing significantly to the health of ecosystems and aiding in the pollination of various plants, including crops and wildflowers.
Their active season is short, typically a few weeks in spring. If their presence is unwanted, simple, non-chemical methods can encourage relocation without harming them. Regularly watering the nesting area deters them, as they prefer dry soil. Increasing ground cover through planting or mulching also makes an area less appealing.