BTB. Osmia caerulescens (Linnaeus, 1758) Commonly known as the “Blue Mason Bee”
Family: Megachilidae.
Female length: 10 to 11m. male length 8 to 9mm.
Flight Period: Late April to Late July. (Bivoltine in some southern counties), peaking again in August. (Males appear before the females)
The Blue Mason Bee is a solitary bee, being a Holarctic species, it is found throughout most of Europe, from Scandinavia, southwards to the Mediterranean and East to Greece. Also occurs in North Africa, into central Asia and North Africa. Widespread in Southern Britain but less common the further north you go.
Habitat: In various habitats the Blue Mason, be can be found on the coast and inland, woodlands, often seen in urban gardens and pathway sidings, with overgrown vegetation.
Flowers visited: Pollen is often collected from legumes, (White clover, Sainfoin and bird’s-foot-trefoils), also other various plants are visited, bramble (Rubus fruticosus), cat-mint (Nepeta cataria), common knapweed (Centaurea nigra), ground ivy (Glechoma hederacea), smooth hawk’s-beard (Crepis capillaris) and snapdragon types.
Nesting Habits: Most types of holes, crevices and cavities that are usually pr-made above ground, in masonry, dead wood, are all prospective nest sites for this species. Also, the hollow stems of plants, especially brambles. Cells are constructed in straight lines plugged with leaf mastic and occasionally flower petals are also used to seal the cell entrance.
The parasitic wasp Sapyga quinquepunctata can often be spotted resting close to Osmia caerulescens nesting sites.