This wasp mimicking thick-headed fly was observed last July in Scott County, MO. This was another interesting pollinator I found moving among the blooms of American jointweed (Polygonella americana).
Physocephala furcillata – A Thick-headed Fly
"What a thousand acres of Silphiums looked like when they tickled the bellies of the buffalo is a question never again to be answered, and perhaps not even asked." -Aldo Leopold
A Thousand Acres of Silphiums 