Osmia inermis (Zetterstedt 1838)
Nests are affixed to stones or rocks. Cell partitions and caps are made of leaf pulp (Cane et al. 2007).
Females are known by the slightly acute angle or tooth midway on the ventral margin of the mandible. Males can be distinguished by the form of the S4, which is strongly truncate and emarginate medially, forming distinct, rounded sublateral lobes.
In the Nearctic, from Sierra Nevada of California north to British Columbia and Alaska, east through Canada to Nova Scotia and Newfoundland south in the United States to Massachusetts, Michigan, the Black Hills of South Dakota, and mountainous areas of Nevada, Utah, and Colorado. In the Palearctic, O. inermis is found from Spain, Italy, and Greece north to the United Kingdom, Norway, Sweden, Finland, and east through Russia and northern China. The related, if not synonymous, species O. ishikawai is found in Japan.