Update 31 July 2017.  Thanks Kathy (Langley, BC).

These photos are awesome pictures of  bumblebees nesting in a bird house.

This is not an uncommon occurrence.  Bumble bees will nest in the ground, inside insulation of a wall, in a bird house or other structure that will keep the weather out.  Bumble bees find these places attractive for nesting if there is either moss, insulation or other nesting material collected by mice.  chickadees prefer and often collect moss their nests.  It dries out into a nice cushioning type material, perfect for their young offspring.  By the way, Joe S. says that if you want chickadees to nest in a bird home, place dried moss into the bird house.  And yes, I tried it with success.  Thanks Joe!

Like chickadees, birds of all kinds bring nesting materials like moss and grasses into their bird house and leave after their young have hatched.  This is a great boon to bumble bees.  This is also a nice way of increasing the number of bumble bees into your garden.

Bumble bees are such cool creatures, often colourful to boot.  Kathy writes “When you see them up close they have an incredible amount of pollen on their back legs.  The opening into the bird  house is 1 1/4″ so you can see how huge they are.”

The large bumble bee is the queen and she chooses the nest site.  She then starts collecting pollen and nectar which she carries on her legs fro her offspring.  She collects sufficient pollen for a brood of about 10, and sits on these eggs like a broody hen.  After 2-3 weeks, the your bees emerge and they begin collecting food for additional offspring.   These cells that the oung bee comes out of, are now used as storage pots for honey and nectar.  These pots hold enough food to carry the colony over for 3-5 days of rain.  Without these food reserves, a bumble bee colony would be in jeopardy every time it rains.

Once the first set of offspring emerge and begin collecting pollen and nectar, the queen now pretty much stays inside the nest and lays eggs and broods on additional offspring.  Offspring can be small or large.  Their size depends on the amount of food they were given when they were developing larvae.  Often people think they are different species.  species are identified by their colour patterns and not by size.

The colony grows for 2-3 months and then starts producing queens and males.  Males can be identified by their yellow and fuzzy (no distinct lines of yellow) heads.  Females have distinct colours and lines on their head and thorax.  When food conditions dwindle, males mate the young queens and eventually the colony dies out leaving moss and debris.   A sure sign of the end of a colony’s life is when you can see males in a colony.

If you hear of someone being bothered by bumblebees, let them know that the colony does not have more than about a month left before they all leave.  Often the timing to clean out a bird nest or cleaning out a shed can be adjusted to make sure that most bees are produced for the following year.

If we can encourage everyone to do this, work around the nesting times of bumble bees, we will have many more bumble bees in our gardens.  What a delight it is to see bumble bees flitting from flower to flower.  How lucky we are to see it.  Lets make it a common occurrence.

This is a guard- watching out for predators.

Bumble bee on the left is cooling the colony with its wings.  The bumble bee on the right seems to be ready to go and gather more pollen and nectar for the young bees.

Coming in for landing.

Resting after a long flight.

Making room for a larger colony by removing excess moss material.

Underneath the moss is a bumble bee colony (below). One bumble bee guard is walking on the surface of the colony.



Summer mason bees removed from their Quicklock-Corn nesting tunnels. This bee uses masticated leaf material as partition material.

 In the fall, when you find summer mason bee cocoons inside your nesting tunnels, the simplest is to clean out the other nesting tunnels and setting the nesting tray back, with the summer mason bee cocoons, in their wooden shelter ready for next spring.

Summer solitary bees in a wooden nesting tray.

Beediverse Emergence Shelter

Emergence nesting boxes made by Dave M. of Port Alberni BC.

An alternative is to gently remove cocoons with a scoop (these cocoons are more fragile then the relatively sturdy mason bee cocoons) and lay them into a emergence box like the one Dave M. from Port Alberni made or into the Beediverse Emergence Shelter (www.Beediverse.com).

By removing these cocoons from their nesting tunnel, you are freeing up valuable nesting space for other nesting bees in spring and summer.

Summer mason bee cocoons placed into a Emergence/Release box, after removal from nesting trays.

Quite a few new mason bee enthusiasts have asked me about nest location.

The best location for nests optimally includes the following:

1) East facing-bees can warm up early in the morning
2) Sunny-warmth provides adult mason bees energy to fly and provides warmth for larvae to eat.
3) Underneath over hang- protects nest and bees from getting wet.

If you don’t have all three factors at any one location, you may have to make a choice.

You may want to try nests at different locations.  This will tell you which is the best location for the bees.

For more detailed information see my book “Pollination with Mason Bees”  pages 31, 49-50.

This nesting tray contains 5 nesting tunnels.  The upper nesting tunnel contains cocoons with a mud partition between each cocoon.  The mud plug at the left hand side of the nesting tray indicates the entrance /exit.  The larger or female cocoons are at the back of the tunnel (RHS).  Note in the next two nesting tunnels, there are quite a number of compartments, not with a cocoon, but with a pollen lump.

The presence of a pollen lump means that the bee larvae died and did not continue its development into an adult bee.  This can be caused by disease, but can also be caused by cool weather.  Young bees need warmth to feed.  A two week spell of cold weather usually means the demise of these bees.  Unfortunately in this case, the pollen lumps were at the far end of the tunnel and these are the female bees.

This year, many people were not able to produce many mason bee cocoons.  I am sure the weather played a big part in this story.

Scoop tool

Scoops are modified screwdrivers and are a boon to harvesting cocoons.

The angle (more like a sine curve) of the scoop ensures that the tip of the scoop slides under each cocoon and lifts them out of each nesting tray.  No other tool does it so easily.  At the same time as removing cocoons, nesting tunnels are rid of the majority of mud and other debris.  This make the scrubbing process a lot faster.

Cocoons are scooped out of nesting trays straight into  a large bucket filled with water.

Scoop cocoons out of nesting trays over a large bucket filled with water.  After about 30 minutes, the water has softened the dirt around cocoons and the dirt drops to the bottom of the bucket.  This is the first step in cleaning cocoons.

Dave M. uses a sieve for the next step.  Using a sieve, a soft stream of water is sprayed over cocoons held in a sieve.  Water removes a lot of debris from cocoons.

Once cocoons are washed, and dried, cocoons can be candled
A bleach wash, drying, screening and candling are the final stages of cleaning cocoons.

A soft stream of water washes a lot of debris from cocoons held in a sieve. This idea came from Dave M. from  Port Alberni, BC

Small and large release box  with piano hinged lids

Small release box with simple lid.  Plastic containers are good for interim storage, but predation dictates a  more sturdy wooden box.

 Hazelnut is in bloom, bulbs are poking out of the ground…..spring must be near! (Vancouver BC)

When setting out cocoons in large numbers, safety from predation  has to be a key consideration.

Rodents can chew through plastic and paper.  Dave M.from Port Alberni, BC uses a  box with a piano-hinged lid to hold cocoons.

When spring arrives, mason bees emerge from the box ready to start pollinating.

The small box easily holds 2-300 cocoons.  The larger  box holds about 1000 cocoons.

It is best not to layer cocoons more than 1-2 deep.  More than 1-2 layers of cocoons make it more likely that newly emerged bees pick up the rare mite from cocoons as the bee exits from the box.

Since the beginning of this blog (Dec 12th of 2010) people have visited from 19 countries.  They have requested 1876 Page views. Below is a list of countries that have visited with the number of page views
USA 925
Canada 829
France 27
Malaysia 21
Turkey 18
Germany 11
United Kingdom 11
Australia 6
India 4
Slovakia 3
Israel, Denmark, India, Romania, Russia, Bulgaria, Brazil, Finland and Greece ( less than 3)

I find this interest quite fascinating.  I know there are Osmia species in Europe, Asia, and North America, but I am not sure if Osmia species exist in South America.  Osmia species do not exist in Australia.  If you have a story or questions please let me know.

Note escape hole of box in foreground and the escape hole in the adjacent box.  Mason bee cocoons cover the base of the box waiting for warm spring temperatures. As the temperature increases, bees chew their way out of their cocoon and then travel towards the light of  the exit hole.  Note empty cocoons.  Dave uses a hinged lid for closing the box.

Female wasps overwintering in an escape box (emergence box).  If left inside box, wasps would eat bees as bees emerge from their cocoons.

Hi Margriet: Look what I had waiting for me when I went to clean out the escape boxes from last year.
Dave M.Port Alberni, BC Canada

Hi Margriet: Here’s a couple of pics I took today. The umbrella had been hanging on the back porch since spring. Nothing is safe around here. I got 6 cocoons and all are good. (4 females, 2 males).  Dave M.  Port Alberni, BC Canada