Solitary Bees

The blossoms are not yet out, but the bees certainly are: all but 32 of my 400 starting cocoons (as of Friday the 9th April). I have been hanging on every birth and watching every bit of progress that I can see, although so much else is happening, I just haven’t really known what to post or write about first.

Last week I was lucky enough to take a week off amidst the start of the emergence, and ‘unlucky’ like most solitary bee fans I know in Europe, to have cold weather. I was also distracted and busy myself looking for a new job. It was frustrating that I had to leave my bees on the best couple of days for interviews in town, but the new job mission was accomplished (phew!). Where I am going has been described by my interviewer/new boss as a ‘hellish situation’, but I have a strong idea of why it was so and how to make the necessary changes given the power to influence (which I got), so I wasn’t too daunted at the idea of putting out some fires. However there were some other sparks and flames I was very happy to contemplate – spring sprang the bee side of the “birds and the bees”. Things seemed to be warming up in all directions.

Where males go first…

With these sorts of bees (Osmia cornuta), males emerge first. Laid at the front of the tunnels, they are more numerous (almost twice as many as the females in my population), and in nature’s design apparently more expendable.

A particularity of bees in general is that the females can choose to fertilise her eggs or not (hence the specialisation of roles according to gender in social bees), and female mason bees exploit this family mechanism by laying numerous non-fertilised (I think) eggs at the front of the tunnels. These are future males.

So far in my little learning curve, I have understood some things about the ‘why?’. It ensures that :

• In the cocoon phase – when the adults have retired – if there is a frontal attack on the tunnel by a parasite or bird, only males risk being lost – essentially the precious future egg-layers placed at the back of the tunnels are protected,
• If there’s a particular bad late frost after strong spring temperatures/before the blossoms are fully open and male emergence occurs (I counted at least 150 early fliers of my 400 cocoons), their superior number ensures that even if many are lost, there will always be some around to meet the emerging females
• the vast majority of females (even if the cocoons are loose by human intervention and not linear in the tunnels) emerge about a week or ten days after the majority of the males, so synchronising their emergence with the opening of the majority of fruit-tree blossoms. It enables them to be fertilised with enough food supply to hit the air flying.

So this choice of the parent female to lay the males-at-front, females-at-back is steeped in natural reasons so that their precious cargo of eggs are laid at the perfect moment in the ecological cycle.

The best day for my 2010 males bees

So why mention the expendable males? Well for this generation of my population their special day here was Wednesday the 7th of April. No means an international day (judging by friends and fans of my project), but something very, very local.

That morning I did my usual peek out of the first floor window – before taking a shower (fortunately I had the house to myself) – and I saw at least 8 bees on grounded and not moving in front of the door below. (Oh, and I have to add that this east-facing window opens onto a closed courtyard so there was no risk of frightening the neighbours.) Anyway I didn’t immediately understand why all these bees were on the floor and what was going on. I went immediately downstairs and outside to see what possible tragedy was occurring. I then realised it was actually solitary bee party – each of those grounded bees was a male pinning down a newly emerged female.

I gently put the partying couples on a wall hanging plant pot at the side of the door with a white tissue (which you see in the video and caused all sort of focussing problems). There were nine in all. Placing them of the pot there was no risk of me stepping on them and they were ‘relatively’ immobile. I then went up the ladder from the outside and found another 3 tucked out of sight. Of course I took some photos wondering if I was finally learning the real meaning of the “birds and bees” (the sparrows were as usual having their morning disputes) and chuckling to myself about how I should name the video (below).

Returning to the first floor window I opened the cigar box that had become the cocoon release zone and realised that there was even one female that was pinned down inside and that couldn’t get out because the male plus herself were too tall to crawl get out of the emergence hole. In fact I believe that all the females had been effectively pinned down before they could even get a chance to fly.

I also counted 26 empty largish cocoons in the cigar box that had come out that morning. I knew this figure because the previous day, I had removed 41 empty ones that had emerged during several days of the relatively disappointing cold week. So effectively it seemed this was the special day for my 2010 generation of males. In the space of one morning the male Osmia cornutas had finally realised their short but frantic existence in the great cycle of life.

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Unfortunately I didn’t have the software to optimise (re-frame, reduce size) of my images of males, nor the film editing software here which explains the delay in posting. However I did optimise some and they are in the Facebook fan page album I have put together on the “Campaign for solitary bees“. So if you have a FB account, why not go and take a look and become a fan? Solitary bees thrive when they get social.