Andrena

Andrena is a large genus of bees within the family Andrenidae. Often referred to as mining bees, Andrena bees are generally solitary, although they frequently nest in aggregations. They are distributed worldwide, with a particularly high diversity in temperate regions.

Characteristics:

Andrena bees are typically small to medium-sized, ranging in length from about 7 to 17 mm. Their coloration varies widely, with many species exhibiting black and brown tones, often with distinctive bands of hair on the abdomen. Some species display metallic sheens. A key characteristic is the presence of a fovea facialis, a felt-like patch on the face alongside the compound eyes. Females possess a scopa, a brush of hairs on their hind legs used for collecting pollen. Males lack a scopa.

Life Cycle and Behavior:

Andrena bees are typically univoltine, meaning they have one generation per year. Adults emerge in the spring or summer, depending on the species. Females construct nests in the ground, typically in well-drained soil. Each nest cell is provisioned with a pollen-nectar mixture, upon which a single egg is laid. The larva hatches and consumes the provisions, pupates, and emerges as an adult the following year.

Andrena bees are important pollinators of a wide variety of plants, including many wildflowers, crops, and fruit trees. Different species exhibit varying degrees of floral specialization, with some being oligolectic (collecting pollen from only a few plant species) and others being polylectic (collecting pollen from many plant species).

Classification:

Andrena is a very large genus, containing hundreds of species. The classification within the genus is complex and subject to ongoing revision. Subgenera are often used to group closely related species.

Conservation:

Like many pollinator species, Andrena bees face threats from habitat loss, pesticide use, and climate change. Conservation efforts aimed at protecting and restoring suitable nesting and foraging habitats are essential for maintaining healthy populations of these important pollinators.