Mining Bee

Mining bees make up the genus Andrena, one of the largest bee genera in the world with well over a thousand described species found across the Northern Hemisphere. They belong to the family Andrenidae within the broader bee order Hymenoptera, and are solitary rather than social, with each female constructing and provisioning her own nest despite often nesting near many others in loose aggregations.

They are notable as some of the earliest bees active in spring, frequently among the first pollinators visiting early-blooming trees and wildflowers, and many species show close specialization on particular plant families, making them important pollinators for specific native and cultivated crops such as fruit trees.

Ecologically, mining bees are valued for their efficient pollination and gentle disposition, and their emergence aggregations, though sometimes numbering in the hundreds of small mounds on a lawn, represent a beneficial natural phenomenon rather than a colony in the social sense.

• Compact, moderately hairy bee, 8–17 mm long, usually brownish, gray, or blackish with pale hair bands on the abdomen.
• Body shape is stouter and less slender than many solitary bees, sometimes causing confusion with small bumble bees, but mining bees are smaller and less densely furred overall.
• Females have a dense patch of hair (scopa) on the hind legs for carrying pollen, visible as a fluffy "pollen basket" look when foraging.
• Nests are identified by small, volcano-like mounds of excavated soil with a central entrance hole, often in loose clusters on bare or thin-grass ground.

Mining bees occur throughout temperate regions of North America, Europe, and Asia, favoring open, well-drained, sparsely vegetated soil such as lawns, garden beds, sandy banks, and woodland edges for nesting. Many species are active for only a few weeks in early spring, timed to coincide with the bloom of specific host plants, though some genera have summer- or fall-active species as well.

Females excavate individual vertical burrows in soil, provisioning side-chamber cells with a mixture of pollen and nectar for their offspring before sealing each cell and moving on. Though solitary, many females nest close together in aggregations that can appear colony-like but do not share cooperative brood care. Mining bees are important pollinators of early spring flowers, fruit trees, and various wildflowers, and are generally unaggressive, with males incapable of stinging and females rarely stinging unless directly handled.

Mining bees undergo complete metamorphosis with a single generation per year in most species (univoltine). Eggs laid on pollen provisions hatch into legless larvae that consume the stored food, then pupate within the underground cell. Most species spend the majority of the year as a fully developed adult resting within the nest cell underground, emerging for only a brief flight period in spring or another season to mate and construct new nests before dying, leaving the next generation to overwinter underground.