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Sunday, May 6, 2018

Blueberry Robber

I learned something interesting about the eastern carpenter bee, Xylocopa virginica. I was walking in the woods in south Jersey in a place near blueberry farms where lots of blueberry bushes grow wild in the understory. There were also lots of carpenter bees hovering around every wooden structure I passed that day; no doubt recently emerged from their overwintering chambers. Some of the bees were visiting blueberry flowers. No surprise there -- who wouldn't want some delicious blueberry flower nectar?                                Click to enlarge.  
Looking closer, you can see the famous white face of a male eastern carpenter bee. Click on this sentence to go to an earlier blog of mine that describes the carpenter bee's life cycle.  Carpenter bees are coming out of their winter homes right now, just as the blueberry bushes are flowering. Great timing! 
I found later that carpenter bees are famous for “robbing" blueberry flowers of nectar. They call it robbing because instead of sticking their heads in and getting covered with pollen, carpenter bees make slits in the sides of the flowers and go straight to the nectar at the base. In the picture above you can see some of these vertical slits on the flowers. Signs of bee robbery! And it doesn’t stop there. Honeybees come to the slits and take nectar. It’s not a total loss for flowers, though, because some pollen gets transferred.

You can click on this sentence to read the abstract of a paper in which it was experimentally demonstrated that the pollen transferred in about three robbery style visits equals that transferred by a blueberry pollinator doing it the conventional way. The study also found that carpenter bee robbery might actually be beneficial because of the large number of honeybees it attracts to the flowers. 

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