Drone flies are bee mimics. You can tell that they are not bees because:
- they have only 2 wings, not 4 like bees
- they do not have pollen sacks on their legs
- their eyes are fly eyes
- they hover; bees do not.
- the flies have stubby antennae (see the two tiny ones in the photo that look like a inequality sign pointing down (< pointing down)) on the front of their head.
Dozens of these flies cover my lobelia pot every day. The kitten tries to catch them all the time but never gets stung. Drone flies are harmless and do not sting. All About Hover Flies is a good article if you would like more information.