ECOLOGY OF SPECIES OF BOMBUS (HYMENOPTERA: APIDAE) IN SOUTHERN ALBERTA: VI. SUBGENUS PYROBOMBUS

Abstract

Of the 21 Nearctic species of Pyrobombus Dalla Torre 11 are known to occur in southern Alberta. Distribution, macrohabitat, microhabitat, and period of nest establishment of the 11 species are compared. The behavioral patterns of camouflaging entrances to underground and false-underground hives, gathering material for nests, constructing first- and succeeding-brood egg cells, producing second-generation colonies, storing honey and pollen and producing wax, superseding intra- and inter-specifically, and mating and hibernating are compared both intra- and inter-subgenerically. Most of the behavioral patterns were common to all southern Alberta species of Pyrobombus; some were common only to certain species indicating a close relationship between these species, and one pattern was common to species in two subgenera but to only 4 of the 11 species of Pyrobombus. Thus, evolutionary trends were indicated. The enemies Psithyrus spp., Volucella bombylans (L.), and inclement weather are discussed.