Unfortunately I have been unable to get a picture so far.
This bee favours plants of the mint family. It is quite small but not slender, it hums very loudly (there were several working the lemon balm and it sounded like a conversation) is probably not more than half an inch, and has dark and verly light gray (or "black and white") markings on its back, on the upper segment looks somewhat like a spot.
They are very fast fliers and remove nectar as rapidly as they gather pollen. And I might add that they carry pollen sacs that are enormous for their size - as large as on the honeybee, though this is a much smaller insect.
I have tried looking online. Most bees that I have seen have black and white stripes. Or they have stripes but appear largely hairless.
Any help is welcome!