Mason Bee

Osmia lignaria Say, known as the blue orchard mason bee (family Megachilidae), is a solitary, non-social bee characterized by its metallic blue or blue-green coloration and robust, almost cylindrical body, typically 10-14 mm in length. Females have scopal hairs on the underside of their abdomen for carrying pollen, a distinguishing feature of the Megachilidae. They do not sting aggressively. Females construct nests in pre-existing cavities, such as hollow stems, wood holes, or artificial bee shelters, dividing them into a series of cells with mud partitions. A single generation emerges each spring.

Mason bees are highly efficient pollinators, active in early spring when many fruit trees bloom. Females collect pollen and nectar, which they pack into individual cells within their nest tunnels, lay an egg on the pollen mass, and then seal the cell with mud. They are solitary and do not defend a hive, focusing solely on provisioning their nests. Their non-aggressive nature makes them ideal for backyard gardens and orchards. Adult bees emerge in spring, mate, and the females immediately begin nesting activities.