This is Brooke, ghostwriting for Mary Dempsey!

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It is a natural extension for those interested in honey bees to also raise Mason bees.  When I heard recently Mary was giving a presentation to a local nonprofit group on Mason bees, I asked if I could adapt her slides to the newsletter and share with all of you.  Here is what I learned from Mary's presentation (supplemented with information from the US Department of Agriculture).

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Osmia Lignaria, the fancy name for mason bees, are good fruit tree pollinators thus also known as orchard bees.  They carry pollen on their bellies rather than their hind legs and they nest in holes using clay to make partitions to seal the entrance.  This mud-building behavior leads to their designation as masons.

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About the size of a honey bee, the mason bee is a very gentle bee, small and blue-black in color.   They are solitary bees, native to North America, an early season pollinator, active primarily from March to May.  Being solitary means each one tends to its own brood, instead of having a queen and worker bees.  There are 140 species of mason bees, they are known for visiting fruit trees such as apples, pears, almonds, and peaches.

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Mason bees are considered more efficient pollinators than honey bees. They are active at a lower temperature flying at 54 degrees (as opposed to the honey bee who flies at 57-59 degrees). Mason bees are true Pacific Northwest insects often flying in light rain while honey bees refuse to face the outdoors on such days.  Mason bees get up early and go to bed late, they are homebodies and it takes fewer of them (than honey bees) to pollinate a fruit tree.

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If you want to provide a bee friendly environment for these busy tiny creatures, pollen should be within 300 feet of their next.  They prefer composite flowers and open petals such as dandelion and fruit tree blossoms.  Mason bees are attracted to early blossoms like blueberry and Andromeda bush, but they will harvest pollen from any flower.  These bees also need a source of mud within 20-30 feet of their shelter.  The bee house should be placed facing the south so it has the most warmth during the winter, and in a position protected from high winds.

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Resourceful and adaptable to their environment, Mason bees use bamboo, house siding, electrical outlets and natural cavities for their nests (they do not drill holes, they use existing cavities).  

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Bees emerge from their nests in early spring with males leading the way.  As with honey bees, the males die after mating.  Three to four days later, females start nesting.  A female will begin collecting pollen and nectar from flowers visiting 75-150 flowers a day.  A female will lay 30-40 eggs in her lifetime and lives 30-40 days.  Inside the nest, eggs hatch in a few days. The larva feed for about 10 days and pupate within the cell.  By summer, bees are in the adult stage and remain there until spring.

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The first brood cells (those that are the furthest back in a nest) will develop into female bees, while those closer to the entrance will become males.  Scientists theorize a couple of reasons for this, one of which is bees suffer nest predation.  The brood closer to the entrance would be predated first.  Because females are more important to sustaining the species, putting the males first increases the survival and specie fitness.

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Enemies (parasites) of the Mason bee are Krombein mites and the Chalcid wasp.  Other threats include habitat loss, pesticides, and climate change.

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The female mason bee has a stinger, but they rarely use it. Because of their gentle nature, they are safe around children and pets and beekeeping protective equipment is not needed.

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They should be ordered in the winter or spring and delivered 2 weeks prior to when you expect your first spring blossoms.  Cocoons should be released when temperatures are consistently above 50 degrees.

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Hopefully this provides some helpful hints as you consider adding (or supporting) mason bees in your garden.  Thank you, Mary, for generously sharing your knowledge about mason bees!