This is lovely weather for bees and they are all making the most of it. A couple of photos from the garden this afternoon illustrate the size range of bees. Using a honey bee as a standard, here is a queen buff-tailed bumblebee (Bombus terrestris). Worker honey bees weigh around 90mg and large queen bumblebees weigh almost 10 times that.
And here is a small solitary bee which looks as though it might be as little as a tenth of the weight of the honeybee.
I couldn't get a photo of the bumblebee and the solitary bee together.