Jordi Bosch & William Kemp 2001 88 pages (B475) For a long time the only pollinator commercially available in large numbers was the honeybee Apis mellifera. This meant that commercial pollination of insect-pollinated crops was dependent on this single species. In the USA the reduction in the number of honeybee colonies due to low honey prices and the introduction of parasitic mites and exotic pests, has led to the commercialisation of the indigenous North American blue orchard bee Osmia lignaria, as a pollinator for orchard crops. Section 1 provides an overview of fruit crop pollination. Section 2 explains the general biology of the blue orchard bee followed by four sections on the rearing and management of the bee. Sections 5 and 6 explain bee densities and the ways to extend nesting periods and progeny production to enhance pollination. The next two sections explain the factors preventing population growth including the (limited) knowledge on pesticide damage, mortality during development and pests, predators and pathogens.