• Family: Megachilidae
  • Tribe: Osmiini
  • Approximate # species in region: 19
  • Common name: mason bees

Osmia is a widespread genus of megachilids, mainly active in spring and early summer. Most are small to medium-sized, pill-shaped, and dark metallic green or blue. Nests occur both above and below ground, including in abandoned bee nests and beneath stones. Although some species are true masons and use mud to line their nests, others employ leaf discs, leaf pulp, wood shavings, resin, or stem pith. Of the nearly 20 species in eastern US, only a handful are currently known to be field identifiable. One of them, the blue orchard bee Osmia lignaria is managed commercially as a crop pollinator of fruit and nut trees.

Species covered:

Scientific NameCommon NamePhenologyHabitatForage
Osmia bucephalaBufflehead mason beeSpringForest, forest-edges, gardensGeneralized, long-tongued
Osmia cornifrons / Osmia taurusHorn-faced mason beeSpringWidespread, disturbed areasGeneralized, esp. exotic trees and shrubs

Species requiring accounts:

  • Osmia lignaria
  • Osmia pumila
  • Osmia georgica