To the right species of bee, this looks like another very aggressive bee, and it goes and bonks it on the head lots and lots of times to try and drive it away, and, of course, covers itself with pollen.
For den rette art af bier, ligner det en anden meget aggressiv bi, og bien går hen og skubber til hovedet igen og igen for at drive den væk, og dækkes selvfølgeligt i pollen.