The species found in Maine generally are some shade of metallic blue. The only exception is Osmia inermis , which is a nonmetallic black. Figure 3 shows several species of Osmia bees. Osmia over-winter as dormant adults. Beginning in late April they begin to emerge from their nest sites.
Males typically emerge before females and are smaller than females.
Mating occurs from early to mid-May. Female bees will begin nest construction several days after mating. Often their over- wintering site of emergence is reused. When females collect nectar and pollen from wild blueberry flowers for provisioning their nests, they pollinate the crop. Males contribute slightly to pollination when they visit flowers for nectar, but males do not collect pollen or assist in nest construction.