A smallish mason bee closely resembling an Osmia species. Length 4-6mm, shiny blue black abdomen, pollen brush beneath abdomen is cream/white (c.f. Osmia spp, pollen brush black or orange). Forewing with 3 submarginal cells, tarsi with an arolium between the claws, spine on hind tibia orange. 

Most solitary bees and wasps are difficult to identify, and can rarely be identified from photos taken in the field.  All red-rated records should include a photo or set of photos of the specimen, illustrating the key characters taken from a standard key, which should also be referenced (e.g. ‘Falk, 2015’).  The full set of key characters are generally not visible in field photos and photos are rarely sharp enough. To aid in the verification of your records, please include face shot, side, top and wings.  The notes should state whether male or female, and explain how the specimen met the key characters.  Although NS may not be able to identify the species even if these reference photos are provided, the photos will be stored with the record and may allow it be identified in future.   Alternatively, NS will accept records identified by a recognised local or national expert, or that have been identified via BWARS’ Facebook https://www.facebook.com/profile.php?id=100065021433202 .  If you have obtained this advice, please note the name of the person/organisation identifying the record in the ‘determiner’ field (e.g. ‘Stuart Roberts, BWARS Facebook’) rather than just a comment of ‘BWARS Facebook’.

The species has been recorded from a wide range of habitats, including, for example, open broad-leaved woodland, heathland edge, chalk grassland and the coast.

Univoltine; late May to late August (rarely September).

Many nests of this bee have been found in dead stems, where the females had excavated the pith to form nesting burrows. Such stems included bramble, rose and ragwort.

Widely distributed but usually uncommon throughout much of southern England and in south Wales (where it is largely coastal); much more sporadic in the Midlands, East Anglia and northern England.

Status in Leicestershire and Rutland not known.