No, not a bee eating a bee. Even better! This is a bee-mimicking robber fly, Laphria, feeding on a honey bee. The fly casually alighted next to me in the garden this afternoon, as though it wanted to be photographed with a trophy kill.
Laphria is an exemplary bumble bee mimic. The flies not only look like bumble bees, they move and sound like them as well.
Canon EF 100mm f/2.8 macro lens on a Canon EOS 7D
ISO 400/800, f/14, 1/125 sec
diffuse off-camera strobe, handheld overhead