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Bees

From MB

I’ve been keeping mason bees for four years now and earlier this month I came across something I have never seen/read/heard about before.

One afternoon I noticed a big bumblebee — a big bugger, about twice the size of a mason bee with a tiger-striped orange abdomen — hanging around my mason bee houses and fussing about at the end of one of the tubes. I later observed the same bumbler entering already occupied tubes on more than one occasion. I figured the bumbler was simply stealing the pollen already gathered by the mason bees — you know: working smarter, not harder.
Then one evening I was checking the mason bee house with a flashlight and noticed that in four of the tubes, there was a thick, viscous liquid inside. The taste test doesn’t lie — it was honey.
I emailed Margriet and asked some of the questions running through my mind: Is this common? Do bumblebees hijack mason bee tubes for themselves?
I already have 20 tubes filled up so I have more than enough mason bees for next year. I’m no interest in killing the bumbler but its behaviour was fascinating.
Since then I did some research and, combined with my observations, I have concluded the bumbler in question is an orange rump bumblebee queen (Bombus melanopygus) who has apparently made an odd choice for a nesting site (image: Queen). She had taken possession of a row of four mason bee tubes, each of which contains globs of honey. If you look inside the tubes in image: honey, the little gleams of light are actually the blobs of honey. (I have a better shot of the honey but I can’t get my email to work on my iphone right now).
She goes in and out of the tubes but has to back out of them because she is too big to turn around inside like a mason bee can.
One evening when I returned home from work I was lucky enough to watch as the queen used her wings to fan the entrance to one of the tubes (image: bumbler1A). I’ve read about honeybees doing this at the entrance to a hive so it was interesting to see. When she was finished, I was able to get the second shot (image: bumbler 2).
There are also now a couple of worker orange rumped bumblebees on site and one of them has taken possession of another tube. They are much smaller — but still bigger than a mason bee — with just a dab of orange on the end of their butts.
I have two mason bee houses located side by side but the bumblers show no interest at all in the other house. The bumblers are now very active as you can see by the heavily stained appearance around the end of their tubes (image: tubes). I believe this is caused by dirt and pollen tracked through the honey by the busy bumblebees. They are still producing honey.
From all appearances, the bumblebees have set up shop in the empty mason bee tubes for the remainder of the summer. I have 10 empty ones left so there still room for expansion.
Thanks Michael B.  for some great photos and some neat observations.-Margriet
Bumbler IA

Bumbler 2



Queen



Honey on base of tubes

Michael emailed me with a question on setting out new nests when the old nests are getting filled.  He asked if adding a nest close to the others would disorientate the bees already nesting at the location.  
I suggested that additional nests are best set out in the visual range and clustered close to the original nests. 
Michael also noted that his bees headed for the tubes first.  Yes mason bees prefer round holes, especially when the substrate is wood or carboard.  Unfortunately the bees’ choice is not always the best for eaze of management. 
Michael’s original question was:
If I need to set out more nesting sites for the Mason bees should I put them next to existing sites, or, put them a bit away from the one’s I originally set out?  The reason I ask is that I am getting many more bees to nest so far this spring compared to last year but I do not want to mess up the bees visual cues to the old sites.  I also know they like to be near each other.  Your thoughts?
Michael’s follow up notes are:
As I mentioned before I was particularly surprised by what happened this spring when most of the O. lignaria emerged at once with a very low dispersal rate.  This activity was in contrast to the last two springs where the dispersal rate was high and emergence rates were very sporadic.
In my nesting set-ups, which I have two of them around my house (see the BEFORE photo), I put 40 cocoons in the wooden house, and 20 cocoons in each of the tube units (80 total of O. lignaria).  There was also 20 of your O. californica cocoons in the wooden nursery house.
I set out all of my bees on April 20 and to my astonishment, almost all of O. lignaria had emerged by April 22, and the first mud nests were made in the tubes on April 24.
The second surprise was that all of the bees decided to move to the tube units (reeds and paper filled tubes).  This is where I was beginning to get concerned that I would not have enough nesting sites.  We had a week of very good weather, and then we had four-five days of cool and damp weather which I then decided to put another tube unit below the existing two tube units (see AFTER photo).
During this cool period of weather, I noticed that all the O. lignaria bees were resting in the tubes, so I kept track of what bees were in what tubes and how far they had gotten along in building their mud nests.  The good news is that when the good weather returned last weekend that all of the existing bees resumed their normal activity and were not deterred by the NEW unit below!  It seems that putting a new nesting house nearby did not distort their visual cues (at least under my conditions).
Also, in taking the pictures of my nesting sites last weekend I noticed the O. californica I purchased from you were beginning to emerge.
I just managed to snap a photo of a O. californica male and female bee doing what a pair of bees are supposed to do .
It might also be my imagination but it appears that the O. californica seem a bit larger than the O. lignaria, and so far all the O. californica bees are headed for the tubes.
Maybe it is some kind of social communication or interaction, but who knows what the bees are really thinking!
Best wishes,
Michael-
Mating Osmia californica

Before
After

Osmia californica comes out late in spring, often their emergence overlaps the latter end of the Osmia lignaria (early spring mason bee) season.

However very little is known about them.  If you’d like to share your photos of Osmia californica, please email them to me and I will get them on this blog.

Here is an update from researcher Mike

“We would very much appreciate if you could place a request on your blog. Coastal B.C. would be convenient, but we are willing to consider anything. We do have a colleague collecting stylopized Polistes in Eastern U.S.A.; that is where we found the large Colletes aggregation I referred to in my last email. Please don’t hesitate to contact us if you think of anything.”

This researcher would like assistance with locating a ground nesting colony of Andrena bees.  (Stylopized bees are parasitized bees).  If you have seen any ground nesting bees, please respond to this web.  Your help is greatly appreciated.  I think he would like the locations to be in the Vancouver region of BC. 

Check out the two links below for beautiful photos of various bee species and stylopized bees.

Hello Dr. Margriet Dogterom,
This year I embarked on an project involving the signalling in Strepsipteran parasites of Polistes wasps. Next spring we would like to expand our research to Andrena bees. Ideally, we need to locate large aggregations to provide a ready supply of stylopized bees. We found one large aggregation that turned out to be Colletes, and another that is not very accessible (It’s on a city boulevard).

Ideally we need to locate colonies before emergence next spring, as the stylopized bees emerge first. Would you happen to know the whereabouts of any Andrena bee aggregations? 
Thank you,
Mike

Photos of stylopized bees

Photos of mason bees and other bees

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