Scottish nests of Osmia uncinata. 31) Stump of a burnt Pinus sylvestris tree containing two nests. 32) Female of O. uncinata on bark with three large exit holes of Rhagium inquisitor, of which the upper two served as entrance to one nest each: nest 1 (left) is sealed, nest 2 (upper right) is being provisioned; note the bark particles that have accumulated below nest 2, indicating the former digging activity of the female. 33, 34) X-rayed bark (left) and dissected nests (right) with nest 1 excavated at the roof and nest 2 excavated at the upper lateral corner of the Rhagium boring; the large dark spots on 33) are the three Rhagium exit holes, the numerous small spots are exit holes of anobiid beetles. The red arrows indicate the entrance to the excavated nesting burrows and the red frames the enlarged section on the opposite image.