Mantises, wasps, moths, caterpillars, frogs--even roaches --all a little slice of heaven to just watch & observe. How could any human being NOT be fascinated? Robin, I think your little fly is some kind of Robber or syrphid, but there's so many varieties. Here's a few critters from my gardens -sorry not all in focus :
Great Golden Digger Wasp on Monarda punctata- Interesting short article about them ---->
http://davesgarden.com/guides/...
Silver-spotted Skipper butterfly
Cuckoo wasp, this one predominately blue instead of the usual green.
Long-haired, toothless, egg-eating little pest that got into my kitchen overnight! LOL