The picture is of a male small sallow mining bee, Andrena praecox, one of the many insects attracted, no doubt, to the pollen of our large male goat willow, Salix caprea, in full bloom nearby..
The trunk of the birch sheds horizontal strips and patches of the thinnest bark and these flutter ceaselessly in the wind while still attached making it harder perhaps for predators to see the dark insects against the ever-shifting patterns of light and shade created by these shifting shreds.
