Cleaning Mason Bees with Brian Campbell March 15, 2013 18:22

Here's a little up-close look at end-of-season mason bee cocoon handling.

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houses courtesy of

 You start with some cute mason bee houses, like the ones shown above.  You can also build your own - all you need is some protection from the elements and a series of cavities for the bees to nest.  Paper tubes work well, as do plastic or wooden trays like the one below.

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each cocoon has its own little mud-walled chamber

Here's a tray full of mason bee cocoons.  You'd have a stack of these taped together so that the grooves become tubes.  Note the light grey clay plugs between each cocoon.  The (larger) females will be toward the back of the hole, and the (smaller) male cocoons near the front so they can emerge first.  The outermost cell is often left empty to deter predation by birds.  The greyish tan cells are full of pollen mites - these pests reproduce rapidly in high concentration mason bee populations and are a primary reason for collecting your cocoons rather than leaving them outside over the winter.  Tray and cocoons courtesy of Brian Campbell (see below).

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Master beekeeper Brian Campbell ( demonstrates how to gently scrape cocoons from the grooves using a "bee scoop" or modified screwdriver.


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Under Brian's tutelage, workshop participants gently wash the cocoons in plain water to dislodge and drown the pollen mites.

 The cocoons themselves are quite water-repellent.  Next, the cocoons are gently towelled dry.  They're surprisingly durable.

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 The end result: clean, dry cocoons

 Cocoons can be sexed with moderate accuracy by size, with females being generally larger.  These can be stored in the refrigerator all winter and until ready to put out in the spring.  This protects them from predators while keeping them cool enough to stay dormant.  A simple humidifying system prevents your dry, modern refrigerator from desiccating them.  At the store we keep them in little boxes within a large paper bag that contains a damp sponge.  As of this writing, we have lots of BC-raised cocoons in stock, and they sell for $16.50 / dozen.


Current (2015) price on mason bee cocoons is $18.00 for a pack of at least 15 cocoons.