Few species of solitary bees make significant contributions to the production of commercial agricultural crops. Pollination needs of commercial agriculture are qualitatively similar but quantitatively distinct from those of the small producer, backyard gardener, and naturalist. Furthermore, the enormous investments of commercial agriculture require that predictable numbers of the that pollinator be available on demand. The alkali bee, Nomia melanderi Cockerell, is the only gregarious soil-nesting solitary bee that has been managed successfully as a pollinator of choice in commercial agricultural production. Nesting site investment and susceptibility of the bee to severe losses because of inclement weather during the nesting period have limited its widespread use. The discovery and development of an alternative pollinator, the alfalfa leafcutting bee. Megachile rotundata (F.), relegated the alkali bee to a secondary role in alfalfa pollination. Historical data and the development of cultural practices for these species are detailed. It is postulated that two adventive Megachile spp. (i.e., M. rotundata and M. apicalis Spinola) have passed through genetic bottlenecks in the course of their establishment in North America, resulting in traits that make them prime pollinator candidates: high reproductive rates, multivoltine life cycle, highly gregarious nesting habits, restricted host specificity, and the establishment of enormous local populations (dispersal disruption).