As some of you may know, there are two families of flies that mimic bees and perform some of their pollinating functions. These are the families Bombyliidae and Syrphidae. The flies in the images below are in Syrphidae.
At first I thought the fly below was a yellow jacket, but it turned out to be Eristalis transversa, one of the bee flies. As you can see, this fly is quite large, almost the size of a honeybee. It is feeding on a black-eyed susan where a daddy-long-legs lies in wait. The latter did not move at all the whole time that the fly was crawling around on the flower.
I believe that this fly is in the genus Toxomerus, possibly T. geminatus, because of the pattern on its abdomen. This was much smaller than the other fly.
Finally, here is one non-pollinator, a meadow katydid. I am not sure of the exact species.
These photos and more are also available at my Flickr account. I am willing to be corrected if any insects are misidentified.