Wall Mason Bee

Osmia parietina is mostly black in colour, however possesses ginger pubescence on top of the abdomen. They are a medium sized bee, which can be found in flight between the months of May and July.

Osmia parietina can be found across Europe, however is mostly restricted to upland, hilly and mountainous areas. It has been recorded throughout much of Northern Eurasia including the United Kingdom, Spain, Greece and Russia. Osmia parietina is associated with areas of unimproved grassland, where their primary nectar source bird's foot trefoil (Lotus corniculatus) grows. They also have a preference for upland herb rich pastures and woodland glades. Females build their nests inside the crevices of drystone walls, rock faces and standing deadwood.

Although L. corniculatus is the primary nectar source for Osmia parietina, it has been recorded visiting flowers of other plant species such as: Ajuga reptans, Hippocrepis comosa, Rubus fruticosus, Sedum reflexum, Trifolium pratense and Veronica chamaedrys. The Western mason bee is also one of several host species for the parasitic Northern Osmia ruby-tailed wasp (Chrysura hirsuta).