Technical Abstract: The alfalfa leafcutting bee, Megachile rotundata, is a gregariously nesting, solitary bee that is managed for use as a commercial pollinator of alfalfa. Imported into the United States from Eurasia around 1930, the pollination efficiency of this bee in alfalfa has markedly increased seed yield in the Northwestern U.S. Bees can be stored over winter periods as prepupae and then warmed in incubators in the spring to stimulate pupation and adult emergence. Adult bees are released into alfalfa fields in shelters where nesting material is provided. Leafcutting bees gather nectar and pollen from alfalfa blooms and pollinate flowers in the process. At the end of the alfalfa-growing season, nesting material is removed from fields and bee nests are stored for future use. Good management and hygiene practices are important for successful rearing and use of these bees in commercial settings.