Resin-nesting
Guides
Protosmia
Protosmia is a genus of solitary bees in the family Megachilidae, tribe Osmiini, containing over 30 described species. The genus includes several subgenera, notably Chelostomopsis and Nanosmia. Species within the subgenus Chelostomopsis are broad pollen generalists that nest in preexisting cavities in dead wood or pine cones, using pure resin to construct nest partitions. The genus has a primarily Palaearctic distribution with some species extending into the Nearctic region.