Orchard Mason Bee, Osmia lignaria

The orchard mason bee (Osmia lignaria), also known as the blue orchard bee, is a species of megachilid bee that is native to North America. Its range extends across the Rocky Mountains, where two subspecies are located. The nests of this species are made in natural hollows in which the bees will make separate rooms for larvae by creating walls with mud.

The orchard mason bee can first be seen the early spring months, when temperatures reach about fifty-seven degrees Fahrenheit. Males leave the nest first and remain close by until the females emerge, after which mating occurs. After this, females will leave the nesting site until their ovaries fully develop, which can take up to several days. Once the females are ready, they will leave the area in search of a suitable nesting site, which can occur in many places including key holes, narrow tubing or holes, and cedar shakes.

Beekeepers build nests made from various materials in hopes of keeping female orchard mason bees within their orchards, or in the surrounding area. The materials include paper tubes, reeds, wooden trays, and “bee condos,†or premade bee nests. Natural elements like silty mud are also important to provide for the female bees, which they use the mud to build walls within the nest.

Once a female orchard mason bee has located a suitable nest, she will fly just outside of it in order to locate landmarks, in a display that looks similar to a dance. Once inside the nest, the female will begin to build individual rooms for each egg she lays. Before laying the eggs, the female will gather nectar and pollen from the flowers around her nest preferring those within a close proximity. When there is enough pollen in each room, the female will lay the eggs on top of the pollen stores. Each room is then sealed off with more mud, creating another back wall with each finished room. Eggs are laid in order of their sex, which the female bee can choose, placing fertilized female eggs in the back of the nest and unfertilized male eggs in the front of the nest. Once all the eggs are laid, the female bee seals the main entrance to nest and departs to find a new nest. She will do this for eight weeks, her entire lifespan, laying up to thirty-two eggs in that period.

By the early summer months, the larvae of the orchard mason bee have consumed enough to pollen to develop and create a cocoon, which they wrap themselves into in order to grow into a pupal form. During the fall and winter months, the larvae will continue to develop, consuming their fat stores until they can emerge. Temperatures must be perfect before the newly hatched adults can survive and farmers are known for timing the emergence of fresh spring flowers with the emergence of new adult bees.

The orchard mason bee is a gentle species and will only use its stinger in defense if necessary. This is due to the purpose of the stinger, which acts as a guide for the female to lay her eggs. This species is a good pollinator and is often used in rural and urban settings.

Image Caption: Photograph of what is believed to be a Blue Orchard Bee, taken in New Mexico, USA. Credit: Robert Engelhardt/Wikipedia (CC BY-SA 3.0)