Overview
The Blue Orchard Bee (Osmia lignaria), celebrated across North America as the Orchard Mason Bee, is a gentle, metallic-blue solitary bee renowned as the premier agricultural pollinator of early spring fruit trees. Incomparably more efficient at pollinating apples, cherries, and almonds than non-native honeybees, a mere 250 female Blue Orchard Bees can accomplish the pollination work of an entire commercial honeybee hive of 50,000 workers.
Biology and Physical Characteristics
Osmia lignaria is a compact, robust bee with a striking metallic dark blue or iridescent green-black body covered in soft, pale grey hairs. Unlike honeybees that carry pollen in moist pellets on their hind legs, female mason bees carry dry pollen on a dense brush of stiff hairs located on the underside of their abdomen called a scopa, resulting in extraordinary pollen transfer as they clamber messily over flowers.
Behavior and Ecology
A solitary nesting bee that lives without a queen or hive, each female establishes her own nest in hollow twigs, beetle holes in dead trees, or wooden bee blocks. In early spring, she creates linear rows of brood cells, provisioning each with a loaf of pollen and nectar before sealing each chamber with a smooth, carefully sculpted partition of damp mud (masonry).
Conservation and Human Impact
Common and widespread across North America, the Blue Orchard Bee is increasingly fostered by commercial fruit growers and backyard gardeners through artificial wooden nesting blocks. Because it flies in cold, cloudy weather that grounds honeybees and never produces aggressive defensive stings, it is an indispensable champion of sustainable agriculture.
Interesting Factoid
The Blue Orchard Bee is a pollination superhero: a single female visits over 2,000 blossoms a day and pollinates flowers so thoroughly that just 250 mason bees can pollinate an entire acre of commercial apple orchard.