Fig 1. Osmia cornifrons.

A) Mating pair of O. cornifrons; male above female. Photo credit: L. Russo, used with permission. B) Nest box used to provide shelter for mason bee trap nests. C) O. cornifrons nest opened shortly after nest closure; pollen provision masses with small larvae and eggs are visible; note mud partitions separating pollen provision masses. D) O. cornifrons nest opened after all larvae have completed feeding, defecated and spun cocoons (early fall); each cocoon contains one adult, diapausing bee. Nest entrances in figures C and D are to the left.