The Borage (Borago officinalis) on the allotment is just past its peak flowering. Nonetheless there are still plenty of flowers...and bees. The flowers of some plants can take up to a day refill with nectar after a bee pays a visit, others only secrete nectar at particular times of the day. But Borage refills within a few minutes.

 I sowed both Blue and White Borage. I've read that bees are most attracted to the blue-purple-violet spectrum but they seem to frequent the white in equal measure.

 Borage is visited by bumblebees as well as honeybees. On this patch there were noticeably more honeybees but they are probably more numerous given that a typical hive contains tens of thousands. Note the pollen sac on this bumbler.