While honeybees are famous for their communal hives, many bee species naturally build their nests beneath the ground. This underground nesting behavior is a common and important aspect of many ecosystems, supporting a diverse range of pollinators. These ground-dwelling bees play a significant ecological role.
Common Ground-Nesting Bee Species
Many different types of bees utilize the ground for nesting, with some of the most frequently encountered including miner bees, digger bees, sweat bees, and certain bumblebee species. Miner bees are solitary ground-nesters, meaning each female constructs her own nest, though they often nest in close aggregations. They are generally dark-colored and can have varying degrees of hairiness, sometimes appearing similar to small honeybees. Digger bees are also solitary and known for their digging abilities. They can range in size and color.
Sweat bees are another common group of ground-nesting bees. These bees vary greatly in appearance, ranging from dull black or brown to vibrant metallic green, blue, or purple. Some sweat bee species are solitary, while others can be semi-social or even social. Bumblebees are social bees that typically nest in existing underground cavities. They are larger and often fuzzy, with characteristic stripes of orange, white, or yellow.
Characteristics of Their Underground Nests
Ground-nesting bees create burrows or tunnels in the soil, with the complexity of these nests varying by species. Each female excavates her own individual burrow, though many individual nests might be located close together in what is called an aggregation. These nest entrances often appear as small holes in the ground, sometimes surrounded by miniature volcano-like mounds of excavated soil.
These bees typically choose areas with exposed soil, thin grass, or sparse vegetation for their nests. Common locations include lawns, gardens, and bare patches of soil, often in sunny, well-drained areas. The tunnels contain brood cells where eggs are laid and provisions are stored. Some species, like cellophane bees, line their nest cells with a unique, cellophane-like secretion to waterproof them.
Reasons for Ground Nesting
Ground nesting offers several advantages for certain bee species. The soil provides a stable environment, protecting the developing young from extreme temperature fluctuations and maintaining consistent humidity levels. This subterranean shelter also offers protection from many predators. Bees specifically seek out well-drained soils, as these conditions are ideal for digging and maintaining their burrows.
The availability of suitable soil types and access to nearby pollen and nectar sources are also important factors influencing nest site selection. Many ground-nesting bees are active in early spring, and their emergence is often timed with the blooming of specific flowers, reflecting their foraging needs.
Interaction with Ground-Nesting Bees
Ground-nesting bees are generally docile and pose minimal threat to humans and pets. Unlike social insects that aggressively defend communal nests, most ground-nesting bees are solitary and do not aggressively defend their individual burrows. Female ground bees can sting, but only if directly provoked or handled roughly. Male ground bees, which are often observed flying actively around nest sites seeking mates, do not possess stingers and are harmless.
These bees are important pollinators for both wild plants and agricultural crops. If ground nests are found in a populated area, the best approach is to observe them and allow them to complete their natural life cycle. They are usually active for only a few weeks in the spring, and their nests naturally disappear as the season progresses. Disturbing the area with pesticides is not recommended and can be harmful to these beneficial insects. Simple measures like watering the area can encourage them to relocate, as they prefer dry soil.