This large (approx. 1 inch in length) wasp is in the Sphecidae family, the thread-waisted wasps. By mid-July it, and the closely related S. pensylvanicus (next photo), are common sights around flowers. Both species hunt insects in the grasshopper family and put the paralyzed insects into their underground nest. They are generally non-aggressive, as is true of most Sphecids, and I have spent many hours around them, getting to within an inch of them. However, when protecting their nest site, they may get defensive.