Kelly’s Field Notes
Common Name: Mason Bee
Family: Megachilidae (Greek cheilos meaning lip)
Genus: Osmia (Greek for odor and refers to the lemony smell leaf cutter bees produce when creating their nests - each species creates a unique scent)
Species of Note Near You (There are about 300 species of mason bees! 140 of them live in North America):
Osmia avosetta - they line their burrows with flower petals! They are found in Turkey, Iran, Syria, and Jordan.
Blue orchard mason bee (Osmia lignaria) - named for their efficiency in pollinating fruit trees. It is one of the few native pollinators used in agriculture. This species is common in both eastern and western North America, divided into subspecies.
Horned-face bee (Osmia cornifrons) - native to east Asia
Red mason bee (Osmia bicornis) - native to Europe
Mason bees are small, solitary bees, only about 3/8 to 5/8 inch in length. Males are smaller than females and have lighter fuzz on (setae) on their faces. They are mostly metallic green or blue in color, but some have a similar coloration to honey bees or bumblebees. The mason bee stores pollen in its scopa (pollen basket) not on its legs like other bees, but on its abdomen. Mason bee females have stingers (like all bees, males are stingerless), but they are not aggressive. If she did sting you it’d feel a little itchy. They are so gentle, in fact, that if you are highly allergic to bees and stung by a mason bee the sting would be non-lethal.
Mason bees begin life as eggs in singular nests created by their mothers within naturally occurring tubular cavities, such as hollow sticks, abandoned nests of other insects, or in mason bee homes created by humans. Each female will lay up to 15 eggs in her lifetime. They do not create their own burrows. She loads the nest with a provision mass created with pollen and nectar, a food source for her larvae. Female eggs are laid first, near the back end of the borrow, and then covered to create partitions throughout the burrow. Male eggs are laid towards the front of the burrow and will hatch first. The partitions and eventual end plug of the burrows are made of mud.
Mason bee eggs take 1 to 2 weeks to hatch, the timing is temperature dependent. From there, the larvae spend around 4 weeks eating their provision mass and growing. Once they are ready, they spin a cocoon to transform into an adult. This process takes all summer, from June to September. The adults then hibernate through the Winter to emerge in the Spring once the air temperature has reached 10oC (50oF).
Once the males emerge in the Spring, they remain close to the burrow waiting for the females to hatch so they can mate. The newly emerged females will mate with several males, and begin the egg laying process anew. The males die after mating.
Belly Flop - mason bees bellyflop onto flowers to collect pollen, which gets all over their little bodies. When visiting flowers this brings their pollination percentage up to 95%, destroying the honeybees who have a dismal 5% pollination percentage.
Mason Bees in Culture:
Mason bees are readily available for purchase, but this has led to species being introduced outside their native range and competing with native mason bees in those regions. If you are interested in ordering mason bees to help pollinate your fruit trees please make sure they are the correct species for your range!
“How to Manage the Blue orchard Bee” by the U.S. Department of Agriculture - Free PDF! https://www.sare.org/wp-content/uploads/How_to_Manage_the_Blue_Orchard_Bee.pdf
Carril, Olivia Messinger, and Joseph S. Wilson. Common Bees of Eastern North America. Vol. 123. Princeton University Press, 2021.
Chittka, Lars. The Mind of a Bee. Princeton University Press, 2022.
Wilson, Joseph S., and Olivia Messinger Carril. "The bees in your backyard." The Bees in Your Backyard. Princeton University Press, 2015.
“Blue Orchard Mason Bee.” United States Forest Service, www.fs.usda.gov/wildflowers/pollinators/pollinator-of-the-month/mason_bees.shtml.
Dodge, Chris. “The Small but Mighty Mason Bee.” Portland Audubon, 17 Mar. 2022, audubonportland.org/blog/the-small-but-mighty-mason-bee/
Dunne, Niall. “Getting to Know Our Native Northwest Bees.” Arboretum Foundation, 15 July 2016, arboretumfoundation.org/2016/07/15/getting-to-know-our-native-northwest-bees/.
Frahnert, Konrad Sebastian, and Karsten Seidelmann. “Individual Scent-Marks of Nest Entrances in the Solitary Bee, Osmia cornuta (Hymenoptera: Apoidea).” Insects vol. 12,9 843. 18 Sep. 2021, doi:10.3390/insects12090843
“Mason Bee.” Chesapeake Bay Program, www.chesapeakebay.net/discover/field-guide/entry/mason-bee.
Sedivy, Claudio, et al. "Host range evolution in a selected group of osmiine bees (Hymenoptera: Megachilidae): the Boraginaceae-Fabaceae paradox." Biological Journal of the Linnean Society 108.1 (2013): 35-54.
“So What Is a Mason Bee? (Luzerne County Master Gardener Program).” Luzerne County Master Gardener Program (Penn State Extension), extension.psu.edu/programs/master-gardener/counties/luzerne/news/2015/so-what-is-a-mason-bee.
Zurbuchen, Antonia, et al. "Long foraging distances impose high costs on offspring production in solitary bees." Journal of Animal Ecology 79.3 (2010): 674-681.