Osmia avosetta is a species of mason bee. Osmia californica is a megachilid bee, or mason bee. The intermediate students build and install mason bee homes in the Centre's orchard. Anthidium exhumatum is an extinct species of mason bee in the Megachilidae genus "Anthidium". The usual pollinators are the common carder bumble bee, honey bee, and red mason bee. Like the orchard mason bee, "O. californica" is a solitary nester. The world's largest bee, the giant mason bee, occurs here and on nearby Halmahera. The red mason bee, "Osmia bicornis", is found across the European continent.