My name is Dr Margriet Dogterom and am the founder and owner of Beediverse. I write this blog for all who love bees and who want to learn more about these wonderful creatures.

Monthly Archives: May 2011

Thanks for your questions Barry.  My comments are in blue.
Hi, Barry here.
I have a couple of questions about Mason Bees.  Any help would be great.
I have been raising Mason Bees for 3 years now in Minnesota.
I had purchased them on line.
I started with about 120 to 180 bees and have doubled or tripled my
count.  I have made multiple types of Houses and Traps.
If my Bees fill every hole, reed, tube and cavity I have put out for them
I figure I might have as many as 1000 Bees to store this Fall.

My first question is how long can Mason Bees be kept dormant?  It depends on the amount of fat reserves the bee has- ie the amount of food it was fed during development during the previous spring. 

I would like to start putting some out next year in April and continue
putting out more Bees for a couple of months.

Could dormant Bees be kept in a Small fridge for over 6 months?  Yes, but it would depend on their food reserves in the form of fat reserves.

I pull the Bees houses down in November and store them.
By April it has been 6 months that they have been in my fridge.

I have an old Dorm Fridge that works really well for keeping them at a nice 35 to 38 degrees.
This lets them have the “cold snap” they need without stressing them from the great outdoor temps.

Second, I would like to know what is the coldest temp that Mason Bees could survive?
I’ve seen Minus 26 degree temps just in my backyard here in Minnesota.
I have heard that 10 degrees and colder can do them harm, any thoughts on this?  I would generally agree with your statement.  My recommendation are to keep mason bees away from minus temperatures.  A good way of doing this is by keeping them in the fridge.

When I open my house to clean and collect my Bees, should I separate any different bees like Masons and Leafcutters?  I separate them out because mason bee cocoons can be cleaned and leafcutter bee cocoons cannot be cleaned.

Should I put them out at different times during the year?   Since setting cocoons out at the nest makes them vulnerable to predators, I would set them out close to their natural emergence time.

Bonus Question, how far will Mason Bees travel away from the bee house to find Pollen?  I have read they can fly about 300 meters to 1500 feet.  Is this about right?  It depends on the density of bloom and availability of food.  In a commercial blueberry field most mason bees travel within 500 feet.  In a suburban lot, bees were observed to fly a distance of 3 lots, which is no more than about 300-400 feet.  

Thanks for your time.

This is a question I have been asked several times-  How to help mason bees find their nest.

In nature, mason bees do not have this problem since one nest is on a post next to  the wood pile and another nest might be in a wall of a shed. But when many nests are right next to many other nesting holes bees often have a problem of returning and finding their ‘home’.  

You may wonder what a ‘lost bee’ looks like.  The bee acts ‘lost’.  It flies into one nesting hole, immediately flies out and goes into another nesting hole.  This continues for several minutes.  This searching behaviour is a waste of time.  When a simple design has been added to the nest, it takes only about 30 minutes before the bee goes directly to her nest with no searching whatsoever.

All you need is some acrylic paints.

The trick is to provide a simple design, and not a complex design that it does not help the bee at all.

I will now go to work and create some simple designs on nests that will help mason bees find their home.

More later.

In a previous blog I wrote about 6″ diameter petri dishes that are so handy for storing large numbers of cocoons.  When you have a large number of cocoons, it is  wise to keep them refrigerated.  Refrigeration keeps them away from predators and keep them relatively safe. BUT I must reiterate that humidity has to be at least 60%.  In order for cocoons to survive, there has to be at least 60% humidity.  Any thing less than that will kill the bee over time.  Use a fridge  that you manually have to defrost .  These fridges keep humidity over 50%.  As a precaution keep a container of water inside the fridge.
Petri dish for storing 100-200 cocoons
A stack of petri dishes filled with cocoons are placed inside this fridge for storage.  Cocoons are then placed into release houses ready for release.
This is the freezer compartment in a manual-defrost type fridge.  The stack of petri dishes are just below this compartment.
Use a thermometer to let you know when temperatures are too warm or too cold.
A container filled with water ensures a greater than 60% humidity.
Release houses filled with 100 cocoons are held in the fridge, prior to  releasing into the D27 yurt.  The cardboard straw temporarily plugs up the front entrance of the Starter Cottage.

Under certain circumstances, it is handy to have a container into which you can place escapee mason bees.

These escapees are mason bees that have emerged inside the house and are buzzing around in the basement or in kitchen.  Not that they are going to do any harm, but it is nice to be able to set them outside so they can go about their business.    This handy little gadget can easily be made by anyone.  It requires a pop bottle and a pair of scissors.

Find a pop bottle.
Cut pop bottle into half with a utility knife of a pair of scissors.
Invert the top into the bottom.  Make sure that the ‘top’ of the bottle
is about 1″ above the base of the bottle.
Mason Bee catcher ready for use.
Add any escapees into the Catcher, and release them outside.
If the bee is very active, slow it down by setting it into a fridge for
about 30 mins and then release.
A happy bee that has just been released.
The opening in the roof of the D27 yurt
is used by mason bees that are
 exiting the yurt and is for venting any excess
 heat during the summer months.
D27 yurt is ready for spring.
The silver colour of the tarp is on the outside.
The blue colour of the tarp faces the inside.  Two posts
protect it from severe winds.


A row of Highrises are attached at the roof line.  This is the  warmest position inside the D27 yurt.  Release houses with cocoons sit on top of Highrise homes.
Temperature at roof line is 85+F
Outside (N) temperature of 64F
Temperature one foot down from roof line is 76F
Temperature  2 feet down from roof line is 71F.

The increase in warmth of the D27 YURT can only be a boon to mason bee production

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