Monday, October 15, 2007

Mason Bees

Mason Bee with mites

Mason Bees (Osmia lignaria) are an early spring pollinator, they are a small blue black solitary bee that we see in our gardens when the fruit trees are in bloom.

With the crash of Honey Bee populations in North America their role has become more important since with better pollination we will get larger more abundant fruit tree yields and our other
plants and trees will be happier.

Mason Bees are very efficient pollinators, better than Honey Bees for a couple of reasons, one is they fly in colder weather so their better for early spring pollination, also they gather the pollen differently, instead of pollen baskets the pollen gathers on the stiff hairs of their abdomens, since its packed looser than on a pollen basket it tends to rub off when visiting flowers allowing for better pollination.

We can increase the population of Mason Bees in our yard by providing them housing, they like a clean hole 5" to 7" long in wood, 5/16" in diameter, one female be will use one or more holes, she will keep laying eggs till she dies.Depth of the holes are important since the female eggs are laid first then the male eggs, if the hole isn't deep enough there won't be the correct ration of male to female.
Mason Bee on heather

Holes drilled in wood will eventually fill with parasites like the mites in the top picture and the bee survival rates will decline.
I like to use stacked routered boards for bee houses, they are easy to clean and to remove the cocoons for cleaning, I can see the difference on the bees when I take the pictures a lot less mites!
Life Cycle.

The male bees chew their way out of the cocoons when the temperatures are warm enough to wake them up in the late winter early spring, the males then wait for the females to emerge and mate with them as soon as they are out.

Once mated the females find a mud supply and a hole, they first seal off the back of the hole with mud then proceed to collect pollen and build a pollen ball that they lay there egg on, once the egg is laid she will seal off that chamber andMason Bee House start collecting pollen for another pollen ball, she will continue this for as long as she can, once the hole is filled she will seal the end with mud then start another hole.
The eggs will hatch and the larva will consume the pollen, then spins a cocoon out of silk, by fall the fully formed bee will be in the cocoon waiting for spring and warmer weather.

Bee Houses.

I like to make my bee houses out of cedar, I rout the slots with 5/16" half round milling bit, its hard to find 5/16" round router bits. I just rout a long board then cut the boards to length after, then slide them in the box, its all dark inside just like the bees like it, you can wrap your boards in black tape if there is any light shinning into the holes.
Where I live a south facing wall under the eaves works best, keeps it out of the rain, and they need the heat from the sun to get active.

Its also good to put a predator guard in front, it can be some hardware cloth with 1/2" holes or a cover with a hole for the bees to get through. A woodpecker can do a lot of damage. 

You also can build in a compartment for the cocoons so they will be safe when you put them out.
Mason Bee cocoon trays
Cleaning and Storing the Cocoons.

First I take apart the bee houses and remove the cocoons with a plastic scraper made for the job, I separate anything that doesn't look like Mason Bee cocoon. then separate the cocoons from the mud.
Mason Bee cocoons

Mason Bee cocoons

Cocoons in there trays, the yellow material is pollen and the white spots are mites.

Mason Bee cocoons

Mason Bee cocoons

First wash the cocoons in tepid water to remove the mud and soften up the other contaminants.
Mason Bee cocoons
Cocoons after first wash, still lots of mites and pollen attached.

Next I dump out the dirty water and fill the tub with a weak bleach solution ( four liters of tepid water and a cap full of bleach), I place the cocoons back in and agitate them around, I use a small sieve and scoop some up and swirl them in the sieve this loosens the attached material, then I rinse under tap tap and place on some paper Mason Bee cocoonstowel for inspection.

Mason Bee cocoons

I check for mites and other contaminants, dump out the old solution and fill the tub up with some clean weak bleach solution a
nd repeat till there nice and clean, look for small dots on the paper towel, you want less than 10 per square inch, these are the small mites.

Looking a lot cleaner.
Mason Bee cocoons
This years cocoons drying getting ready for storage, I would have had more but the woodpeckers consumed some fo them.
Mason Bee cocoons


I place them in the fridge in a sealed container, with some paper towel, once in while I will take them out and give them some air, to much moisture and they will go moldy but you don't want them to dry or the bees will die, if they do go moldy rinse them in week bleach solution again and they will be fine.

Almost all my cocoons had healthy bees this year so this worked well, so I did the same thing this year and took pictures to document the procedure, please feel free to ask questions or contribute more information, or share what you do.

I recommend the book Pollination With Mason Bees
by Dr. Margriet Dogterom, I use it as a reference.


Martin said...

One thing I didn't mention is there fun to watch, so its a good idea to place the houses were you can see them, we have them on our front porch.

A female bee has her hole and the other bees won't use it, you will see them go in the wrong hole sometimes by mistake, they will back out and go to the correct hole.

When they go to the hole with a belly yellow with pollen then its a pollen trip but if there is no pollen then she probably has mud.

Martin said...

If you have cocoons don't put them out all at once, if you get some bad weather after some warm weather and the bees have come out they can die if it gets too cold for too many days in a row and they can't forage for food.

I made that mistake last year so I will release them in bunches next year when the fruit trees are flowering.

Unknown said...

I started raising mason bees last year. A great hobby, and good for the country to build back up our native pollinator population.

Regarding putting them out and then getting hit with excessive cold for a number of days. I'm no expert at all, but I read you can put your own food in their container for them in emergency situations like this. I think you can just use ordinary table sugar, and maybe a small supply of water (which would have to be refreshed if frozen). Don't know, haven't had this problem yet.

In the first year I had a 7 fold increase in population. I can't wait to see what happens this year.

Giterdone said...

Wow this is exactly the information I've been looking for. I started with my first mason be house and 20 mason bees this past year. Now I need to look after them for the winter and you've showed me just that. I'm also planning to make some houses for family and friends and I've been planning something similar to yours. Instead of using tubes, I'd rather be able to take apart and clean the same way. Thank you and I'll be checking back again.

Eric Williams said...

Great site! What do you feed the larvae when they hatch since you removed all of the pollen?

Martin said...

The only pollen removed is from the the larva that didn't work out so there is pollen still there, the ones that survived eat all the pollen then turn into bee's, when the bee's come out of the coccoons in the spring they go find there own food.

Martin said...

Just an update, I am still doing Mason Bee's with this method and get at least a thousand cocoons every year, works great.

And the bee's are always nice and clean, not covered in mites, you can tell the wild ones they are usually carrying a large amount of pollen mites.

I don't always get to them in the fall and have found out as long as you keep them cold you can wash them up anytime.

Anonymous said...

Your attention to detail, and care with the bees, are all so very much appreciated. I have been looking for info, how to provide safe & healthy habitat for mason bees. Your information is just great. Thanks.