Robber-fly

I was doing more plant surveying at the reserve today. When I came to wind up one of the measuring tapes I found that a Robber-fly had taken up temporary residence while it sucked the life out of a much more tiny fly. It was very reluctant to move, so at least I got a good photograph before dislodging it. It looked like the little fly made a vsuccessful escape when I did this. I haven't managed to work out the species yet.