I caught this fly a few days ago and when I looked at it on my PC I noticed there was something odd about it.
I think it is a narcissus fly (judging from the pattern of veins on the wings) though the abdomen is not as in my field guide. But what disturb me is the middle leg nearest the camera. It emerges from the thorax half way up the side, not at the bottom where the other legs are. It also doesn't seem to have any joints, but that may simply be that the fly has it extended. Is this normal or a freak?
Thanks jaguarondi! I was about to reply with the same ID: Eristalis sp., looking like E. tenax. I have prepared a photo with the details:
So, 1 is the front leg, 2 is the middle leg, 3 is the tip of the hind leg, stretched under the wing, 4 is the insertion of wing, not leg, 5 is the place where the hind leg dissapears under the wing, but it looks like it continues because the wing is thicker at its front.