Bees exhibit remarkable diversity in their nesting habits, extending far beyond the familiar image of honeybee hives. While some species construct nests in trees or human-made structures, many others choose different environments. A significant number of bee species build their homes beneath the earth’s surface, revealing a fascinating aspect of their natural history and ecological adaptations.
Types of Bees That Nest Underground
Many bee species nest underground. Mining bees, belonging to the genus Andrena, are prevalent ground nesters, often recognized by their fuzzy bodies and the small mounds of excavated soil marking their nest entrances. These bees are solitary, with each female constructing and provisioning her own nest.
Another group of ground-nesting bees includes digger bees, such as those in the genus Anthophora. Sweat bees, comprising a large family known as Halictidae, also frequently nest in the soil. These bees vary in size and color, with some species displaying metallic green or blue hues, and they often create communal nesting aggregations. Certain bumblebee species, like some members of the genus Bombus, also utilize abandoned rodent burrows or other subterranean cavities for their colonies.
Characteristics of Underground Bee Nests
Underground bee nests begin with a small entrance hole on the soil surface, sometimes surrounded by a small mound or “tumulus” of dirt. From this entrance, a main tunnel descends into the ground, which can extend several inches to over a foot deep depending on the species and soil type. These tunnels branch off into individual cells, each constructed by the female bee.
Each cell serves as a nursery for a single bee larva and is provisioned with a mixture of pollen and nectar, known as “bee bread.” The architecture of these nests can vary, with some species creating simple, unbranched tunnels and others forming more complex, multi-celled structures. Ground-nesting bees prefer well-drained, sandy or loamy soils that are relatively undisturbed, aiding excavation and nest stability.
Advantages of Underground Living for Bees
Nesting underground provides several benefits for these bee species. The subterranean environment offers protection from a wide array of predators, including birds, rodents, and ants. The earth acts as a natural barrier, making it more challenging for predators to locate and disturb the developing brood.
The soil provides a stable thermal environment, insulating the nests from extreme temperature fluctuations. This insulation helps protect the developing eggs, larvae, and pupae from both scorching summer heat and freezing winter cold. The underground location also shields nests from adverse weather conditions such as heavy winds and torrential rains. This stability ensures that the delicate developmental stages of the bees can proceed largely undisturbed.