Setting out cocoons- SMALL scale verses LARGE scale

Mass release of alfalfa
leaf cutter bee cocoons.

I started this article some time ago, before I had all the pictures in place.  Even though most mason bees have been set out, I think it is good to compare mason bee release systems to the commercial Alfalfa Leaf cutter bee industry mas  release system.  I think we can learn a lot from the 50 year old alfalfa leaf cutter bee industry.

How to set out bees, still in their cocoons, depends on quantity of cocoons, type of nests and whether predators exist in the area.

Leaf cutter bee nests

Alfalfa leaf cutter bee producers in the Canadian Prairies, usually mass release leaf cutter bee cocoons on trays.  Thousands of cocoons are placed on trays.  Trays are set up inside yurts or similar structures that house leafcutter bee nests. Three weeks prior to setting cocoons out, leafcutter bees are put through a warming period so that bee emergence is relatively fast.  Trays are out for less than a week.  A mere 7 days or so is little time for winds and predators to upset the trays full of cocoons.

Prairie yurt with a tray of cocoons
set on top of nests.

It is a different story with mason bees.  Emergence is often longer than a week, especially under cool spring temperatures.  The number of cocoons set out are often  less than a hundred or several hundred and less often in the thousands.

Setting out a few cocoons (less than 100) small vials with a bee size hole in the lid works well.  Plastic vials are usually rodent proof.  The space underneath the roof of the Beediverse Highrise  is a great place to place the vial full of cocoons.  This space is protected from the sun, but receives the heat through the roof.

the Highrise roof protects vials
of cocoons from
predation and sun.

Beediverse Emergence box
protects cocoons from predation
and the elements.

When setting out 100 or more cocoons, small vials are too cumbersome and too time consuming.  It would be very easy to set out cocoons in open trays.  I have tried setting cocoons out in trays, even in covered trays, but it has been less successful.  Their extended emergence becomes problematic.  Winds sometimes tip trays onto the ground  Trays also make cocoons more vulnerable to predation from animals such as spiders, squirrels, mice, and wasps.  To decrease the chance of predation a wooden box with an exit hole such as the Beediverse Emergence Shelters gives the best result.  Two are sold for $19.95.

Small and large release boxes.
Dave M.  Port Alberni BC

I find these extremely handy.  I fit about 200 cocoons into each one.  I make notes on the outside to tell me where cocoons were produced.  This is handy because after spring emergence, I can check what the emergence was the previous spring.  Emergence should be 95% or more.

David M. from Port Alberni uses a square box with a hinged lid.  Each box, with two layers of cocoons, holds about 2000 cocoons.

If you have a system you would like to share with our readers, email me a description and pictures.