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.
Alle giuste specie di api, questa sembre un'ape molto aggressiva, ci va e ci sbatte contro la testa per scacciarla via, e, ovviamente, si ricopre di polline.