Red Mason Bee
Osmia bicornis

Osmia bicornis is a species of mason bee, and is known as the red mason bee due to its covering of dense gingery hair. It is a solitary bee that nests in holes or stems and is polylectic, meaning it forages pollen from various different flowering plants. These bees can be seen aggregating together and nests in preexisting hollows, choosing not to excavate their own. These bees are not aggressive; they will only sting if handled very roughly and are safe to be closely observed by children. Females only mate once, usually with closely related males. Further, females can determine the sex ratio of their offspring based on their body size, where larger females will invest more in diploid females eggs than small bees. These bees also have trichromatic colour vision and are important pollinators in agriculture. Source
Where it is now
No records in the last 8 weeks. It may be out of season where the observers and sensors are.
See the Red Mason Bee on the live map
Arrival dates
The week it was first heard regularly in each region, after at least six weeks away. Dates differ from south to north, so a region has a range.
| Region | First arrival | Last arrival | Typical peak | Areas |
|---|---|---|---|---|
| Europe | 9 March 2026 | 13 April 2026 | 13 April 2026 | 5 |
Figures are effort corrected and come from automatic sound identification, which makes mistakes. How this is measured and how it compares with human observers.