Mason Bees: Using an Oregon Native Species to Pollinate Your Garden

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Mason Bees are an interesting lot.  They're an important native pollinator, and because they are native, they're especially "tuned in" to some of the early-blooming native plants around Portland - like red flowering currant. 

They differ from the better-known honey bee in several ways.  First of all they're solitary - each female builds it's own nest, and there are no worker bees to tend them.  And because they make no honey that needs protection (or maybe as a result of all this freedom and autonomy) - mason bees are also kinder and gentler than honey bees.  They don't sting unless they get trapped in your clothes or get pinched (and who goes around pinching bees?).  One other way mason bees differ from honey bees, is that mason bees do not travel long distances from the nest to collect nectar and pollen.  That makes them ideal for pollinating your yard, if you can convince them to stick around and build their nests.

There are over 130 species of mason bees in North America.  One species present in the Portland area is the orchard mason bee (Osmia lignaria). 

Female orchard mason bees like to build their nests in narrow tubes, such as holes left by woodpeckers or insects.  (But you can build or buy houses to accommodate them in your yard - read on.)
  
After finding a suitable tube, they pack in provisions of pollen and nectar, lay a single egg, then they create a partition with mud.  After repeating the process several times, the tube is sealed with more mud, and the bee moves on to another hole. 

During the spring and early summer, the larvae will consume the provisions, then spin cocoons around themselves as they prepare to become adult bees.  The bees will remain in their cocoons throughout the fall and winter before emerging in the spring.

You can encourage the production of more mason bees - and boost the yield of your fruits, vegetables, and flowers - by making or buying bee houses to attract the females.  They can be as simple as a bunch of holes drilled in a block of wood, or something more substantial, like one of the commercially available mason bee houses - some of which have windows that allow you to see inside the tubes, to check the health of the cocoons. 

Interested in building a bee house?  Or would you like to know a local source for bees and houses?  Read all about it, over at Neighborhood Notes.

I can't wait to try this.  I'll let you know how it goes, but in the meantime - has anyone else raised a happy brood of mason bees?