The gray hairstreak is probably the most common hairstreak in this area. Hairstreaks are not as common as eastern tailed blues and spring azures, for example, but late in the summer you can almost always find a few if you look closely.
Gray hairstreaks seem to like the weeds you might find in a prairie--golden rod, partridge pea, etc.
This is one of the few butterflies that becomes common enough to be a crop pest, and its caterpillar is also known as the "cotton square borer". The young eat a huge variety of host plants.
I am not sure how well this photograph translates on your computer. Since I scan the image from 8x10 prints, and since I use jpg files, I am sure that a lot of the detail is lost.
I have an 11x14 print of this butterfly, made directly from the slide that I am especially proud of. In it, you can clearly see the hairs on the fringes of the wings, and the hairs underneath the wings. If you look closely, you can see the individual scales on the wings.
I am in a camera club which is associated with a number of other camera clubs. We exchange prints in contests. I have entered this print in the contests (nature category) a couple of times, but it hasn't won anything yet. Butterfly pictures never do well.