Wasps are closely related to bees and ants, and some can be difficult to distinguish from their cousins. In this case, the long body makes me pretty sure this is a wasp (though body length is not always a good cue), but I don’t know what kind of wasp it is.
A wasp on purple prairie clover. The Nature Conservancy’s Platte River Prairies, Nebraska.
Most wasps are parasitoids, which means they capture and paralyze prey with venom from their stinger and then feed that still living, but paralyzed, prey to their wasp larvae. Usually, wasps specialize on a particular group of invertebrates (spiders, cicadas, grasshoppers, etc.). As with most insect groups, wasps are more abundant than you might think, and if you really start looking for them, you’ll find them all over. Most are not aggressive toward people and will sting only if you force them into it.
While the larvae of parasitoid wasps feed on paralyzed invertebrates, adults feed on pollen and nectar, and are pollinators for many plants. The one in the above photo, for example, has pollen stuck all over its face and body.
The Prairie Ecologist 
incredible picture! Much patience must be involved.
A friend who studied them, told me that some wasps are so tiny, even if you noticed it, you’d probably think it was a fly.
It is quite likely Sphex pennsylvannicus,
http://bugeric.blogspot.com/2013/01/wasp-wednesday-great-black-wasp.html
Chris, I really enjoy your e-mails! Thanks, Gabe Brown Bismarck, ND
This isn’t the usual way insect parasitoidism is described. Wasp parasitoids do not paralyze their host; their larvae feed internally or externally on the free-living host, which goes on about its usual business until near the end. Wasps that provision their young with paralyzed insects are generally categorized as predators.
Robert – thanks for the comment. I hadn’t heard that distinction before. I guess I’ve always considered the “feeding on a living host and eventually killing it” criteria to define parasitoidism, not the free-living part. I appreciate the clarification.
Hi Chris, I was told when I first arrived in Texas of a tool for small patch burning. It’s shaped kind of like a house with a chimney and can be pulled behind a tractor — maybe I should have said micro-patch burning. I’ve looked everywhere and can’t find it and sadly don’t recall the context of the discussion. It would be ideal for our prairie in the middle of urban Fort Worth. Thanks, Karen
Karen C. Hall, Ph.D. | Applied Ecologist | BRIT® | 817.332.4441 x247 | 817.332.4112 fax | BRIT.org | 1700 University Dr., Fort Worth, TX 76107-3400 USA | Think Before You Print
Karen, not sure if this is what you were thinking, but it’s what I’ve seen advertised. I’ve not seen it in action. http://www.firebreak.co.za/SA/index.htm
http://www.fws.gov/fire/news/sd/newsitem2.shtml
This could be a Sphex or it might be the related genus of somewhat smaller wasps Isodontia. There’s no scale, but measured against the Dalea inflorescence, I’m leaning toward the latter. Both are Orthoptera hunters; Sphex prefers katydids, Isodontia prefers crickets. It looks like she could have a bad case of mites on her thorax, by the way.