In 1997, the Cowichan Community Land
Trust Society (CCLT) initiated the Blue Orchard Bee Initiative.
CCLT is promoting a friendly addition to your farm or garden by
informing people about these special bees and how to provide habitat for them.
The Blue Orchard Bee (Osmia
lignaria Cresson) is a gentle, solitary bee native to western North
America that has been getting a lot of attention lately.
"Why all the fuss?", you might
be tempted to ask, thinking the problem of crop pollination will take care of
itself. Unfortunately, it is not that simple.
As scientists have found, this little insect is very selective in
choosing nesting places. Not
being a borer itself, it searches for ready-made holes, preferably in pine,
fir, or hemlock that are exactly 5/16" in diameter and 4" deep. Not
finding any it will die.
Nesting boxes provide these bees with
much needed nesting sites and can be manufactured either from a 4” x 4”
wooden block or wooden trays with channels cut into one side that are then
stacked to form a single nesting unit.
Wooden
block nests are made from untreated 4" x 4" wood blocks using a brad
point bit. The bee prefers holes spaced ¾" apart from their
centers and must be sealed on one end. By
drilling through the block and screwing a piece of plywood on the end the
sealed end can be removed to make cleaning these nest holes easier and more
effective. Ready-made nesting
blocks are now available at our office.
Alternatively, nesting trays can be made
from pieces of wood measuring 6”x 3 ½” x
¾”. By routering a
channel to form a 5/16” groove ending within ½” of the end of each piece
of wood, nesting tunnels can be created by stacking these nesting trays. (diagram available at our office) Trays should be tightly bolted or
taped together to keep nesting tunnels dark and placed in an additional wooden
casing to prevent predation by wasps. Trays
have an extra advantage of being easily cleaned of mite infestations.
In October cocoons can be removed from trays and cleaned in lukewarm
water to remove any mites. Trays
can then be properly cleaned and the cocoons can be placed in tissue paper in
small cardboard boxes with a small exit hole (the
size of a pencil). Bees will
emerge from their cocoon in the spring to seek out the cleaned nesting trays.
The best place to hang the box is under
eaves with a southern exposure to optimize morning sun and protection from
rain. Blue Orchard bees show a
preference for sunny sites as long as their nesting holes are shaded.
The bee makes several chambers in each
hole, each with an egg and pollen supply.
Starting from the end of each hole, they make a bed of pollen (it’s
food for the larva) and lay a single egg on top of it. Afterwards, they close
this one inch long nursery by erecting a mud wall, separating it from other
consecutive chambers, and sealing the last one with an extra heavy mud plug,
guarding the eggs from predators. Moist
mud must be available nearby to make the rough textured plugs between
chambers. Each Blue
can lay 35 eggs which would fill a dozen holes in your condo.
The larvae hatch and pupate, and develop into adults.
These cocoons remain dormant until the next spring.
The adults are normally active from late April to early June, but
emergence can be delayed to pollinate later crops by refrigerating the nesting
blocks in October at 35-40°F. If
delaying is necessary, the nests should be gently taken down, kept upright,
and put in paper bags with a damp cloth to ensure adequate moisture.
The
Ministry of Agriculture recommends an integrated approach to encourage the
protection and enhancement of habitat for wild pollinators.
Avoiding disturbance to soils and natural vegetation is one way to
protect wild bee habitat. Significant
drops in wild pollinator populations were noticed in certain areas after
serious soil or vegetation disturbances. The goal is to minimize the use of
chemical control for economic reasons in some commercial productions. Nesting
bee boxes can also help, and are being recommended by our current BCMAFF.
Can the Blues be found readily in the wild?
As
soon as the first blossoms appear (sometimes later) and the weather gets
warmer, you should see some activities at your condos.
However, if you don’t find anything of this kind, it will be an
indication that there are no Blue Orchard Bees in your surroundings.
Please contact our office if you are not attracting bees to your condo.
On the other hand, should you see a lot
of activity around your condo, please phone us as soon as possible and an
extra condo will be delivered to accommodate all of the buzzing crowd.
Watching the bees fly by It’s
pure fun to watch the Blues at work. They
are simply tireless, making hundreds of flights per day, stashing pollen into
the nesting holes. Observing the Blue Orchard Bees could become a great
pastime, especially for children, offering them unusual materials for
conversations at school.
