Red Mason Bee
Osmia bicornis
The Red Mason Bee is one of the most common wild bee species in Central Europe, inhabiting diverse environments from gardens to forest edges. It is characterized by dense, fox-red hair on the thorax and abdomen, giving it a bumblebee-like appearance. As a solitary species, it does not form colonies but readily uses artificial nesting aids and wall crevices, which it seals with mud. It is a highly effective pollinator that becomes active even in cool spring temperatures.
Details
Identification
Females with two small 'horns' on the clypeus; males with white facial hair and longer antennae; body densely covered in rusty-red hair.
Social behavior
Solitary; females provide for their brood alone, but often nest in large aggregations at suitable sites.
Diet
Polylectic; uses nectar and pollen from over 15 different plant families, including Rosaceae, Asteraceae, and Sapindaceae.
Spawning substrate
Utilization of existing cavities in wood, stone, hollow plant stems, or insect hotels; sealed with mud.
Overwintering
Overwinters as a fully developed insect (imago) inside a cocoon within the brood cell.
Ecology
Ecological role
Significant pollinator for a wide variety of wild and cultivated plants in early spring.
Natural predators
Birds (e.g., tits), parasitic wasps (e.g., Gasteruption), bee mites (Chaetodactylus osmiae), and skin beetles.
Competitor species
Horned Mason Bee (Osmia cornuta) and other solitary bee species with similar nesting requirements.
Ecosystem service
Highly efficient pollination of fruit crops (apple, pear, cherry) and maintenance of floristic diversity.
Threats
Loss of nesting sites due to building renovation, use of insecticides, and decline in floral resources.
Scientific profile
Profile
Distinguishing features
The species is named after the two small, horn-like projections on the clypeus of the female. As an abdominal collector, the female possesses a reddish pollen-collecting brush (scopa) on the underside of the abdomen. It has a robust build, superficially resembling a small bumblebee.
Habitat
Highly versatile (euryoecious); inhabits gardens, parks, orchards, forest edges, and urban environments (synanthropic).
Protection & threats
Main threats
Use of pesticides (neonicotinoids); lack of nesting sites due to energy-efficient building renovations; decline in floral diversity in agricultural landscapes.
Population trend
Stable to increasing; the species is considered the most common mason bee in Central Europe and benefits significantly from artificial nesting aids.
Conservation measures
Provision of nesting aids (drillings 6-9 mm); preservation of dead wood and mud patches; planting of native spring bloomers and avoidance of insecticides in gardens.