Orange-vented Mason Bee - Osmia leaiana
10mm females, 6mm males. As with all Osmia species, it has a large box-shaped head (similar in size to the thorax). Females have a dense orange pollen brush under the abdomen. Males lack the pollen brush and are generally dark, often metallic green, with ginger hairs. Eyes are black. The tip of the abdomen is smooth (except for the central indent).
The males of O. leaiana and O. caerulescens are very similar. However O. caerulescens males have green eyes (when alive) but these are black in O. leaiana. Also, the tip of tergite 6 is crenulated in caerulescens but smooth in leaiana (except for the central indent).
Records should include a photo, or set of photos, showing the key characters. We will accept records identified by a recognised local or national expert, or that have been identified via the BWARS’ Facebook noting the name of the person/organisation identifying the record (e.g. ‘Stuart Roberts, BWARS Facebook’).
It uses a wide range of habitats, especially sites with plentiful thistles and knapweeds. It can be frequent in gardens and is one of the species that like to exploit bee hotels.
Between May and August.
Nests in cavities in dead wood, walls or cliffs. Adults collect pollen exclusively from Asteraceae.
Restricted to England and Wales. It is less frequently found than O. caerulescens, but occurs in similar habitats.
Status in Leicestershire and Rutland not known.
Leicestershire & Rutland Map
Enter a town or village to see local records
MAP KEY:
Yellow squares = NBN records (all known data)
Coloured circles = NatureSpot records: 2025+ | 2020-2024 | pre-2020
UK Map
Species profile
- Common names
- Orange-vented Mason Bee
- Species group:
- Bees, Wasps, Ants
- Kingdom:
- Animalia
- Order:
- Hymenoptera
- Family:
- Megachilidae
- Records on NatureSpot:
- 35
- First record:
- 12/07/2013 (Helen Ikin;Steve Woodward)
- Last record:
- 23/07/2024 (Nicholls, David)
Total records by month
% of records within its species group
10km squares with records
The latest images and records displayed below include those awaiting verification checks so we cannot guarantee that every identification is correct. Once accepted, the record displays a green tick.
In the Latest Records section, click on the header to sort A-Z, and again to sort Z-A. Use the header boxes to filter the list.