y should forage for pollen during the period of cherry and apple bloom and afterwards, if sufficient other flowers are available to them.
For large populations for orchard pollination, the nests should be under humid refrigeration at 35 to 40° F. This will permit control of emergence time and reduce predation and parasitism by the insect enemies of the bees. Do not place the nests in storage until September or October to assure complete development of the adults. The following spring, place the boards in the orchards in plywood shelters facing east to catch the morning sun. To hasten emergence, incubate the boards at room temperature for 24 hours before placing the bees in the orchard. The boards and some new nesting material should be in place a few days before apples begin to bloom, or earlier if other fruit bloom such as cherries, is available. Provide 500-1000 filled holes per acre. These should contain 750-1000 females, assuming an average of 1 1/2 females per hole. Males also visit flowers, but they do not live long and are not as effective as pollinators. Competing flowers such as dandelions should be mowed as soon as the fruit begins to bloom.
Developing large populations of the bees may be a slow process under orchard conditions; the short duration of bloom does not allow the bees to accomplish maximum reproduction. The orchard mason bee also has a tendency to fly away rather than using or reusing nests in the near vicinity. However, relatively large populations have been developed in 2 or 3 years in urban situations. Once established, orchard bees will nest in containers filled with large-diameter drinking straws or paper tubes folded in half.
Orchard Mason Bee, Osmia lignaria. This is a megachilid bee that as do other mason bee makes nests in reeds and natural holes, creating individual cells for their brood that are separated by mud dividers. They are unlike carpenter bees in that they cannot drill holes in wood. O. lignaria is a common species used for early spring fruit bloom in Japan, Canada, and t