The species is most active during the spring and early summer although it may be seen into late June. Despite being classed as solitary, these bees can be seen gathering, or aggregating. The female is larger/broader than the male and has two large horns on the head. The male has a white tuft of hair on its face. The female has a much smaller sting than honeybees or wasps.
Osmia rufa nest in preexisting hollows, choosing not to excavate their own, and have been known to nest in key holes, empty snail shells, plant stems and empty beetle hollows. Male larvae are placed in front of the females within the nest allowing the males to emerge first in the spring. These bees store mostly pollen moistened with a small amount of nectar which is eaten by the larvae during the summer before they rest through the winter in a cocoon. The female will create six to eight cells in four to five different nests in her short life.
Osmia rufa is found in England, southern Scotland (possibly northern Scotland as well), Wales, mainland Europe, Sweden, Norway, North Africa, Georgia, Turkey and Iran.