Sighted April 12, 2018, San Juan Island, WA. Blue Orchard Mason Bee (Osmia lignaria). These are important early (native) pollinators. Adults hibernate overwinter and emerge from March to May. Blue Orchard Mason Bees are being managed as orchard pollinators as they are excellent at pollinating fruit trees such as pear, cherry, plum, and apple, as well as quince and others, including blueberries. Blue Orchard Mason Bees and other solitary bees in the genus Megachilidae (like leaf-cutting bees) carry pollen on their bellies instead of special baskets on their hind legs like honey bees. The Blue Orchard Mason Bee use tubular cavities for nests, partitioning each brood cell with a wall of mud. Although similar in size, Blue Orchard bees are easy to distinguish from honey bees because they are metallic in coloring, often dark blue or blue-black.
Read more about Blue Orchard Mason Bees (Osmia lignaria) here: