I went up to Bear River again to find these and located the male and female together. The smaller male is in the background and the larger female is in the foreground. The first photos I submitted that I took on July 12 are of the larger one - female.
This is what Chuck Holliday said about the above photo:
"Not only can we use your picture, but it's very important to us. The male Sphecius grandis (western CK) is in the upper left and the female is in the lower right of the picture. We've seen this unusual abdominal coloration before in CK males in Big Bend, Texas, but not in the females and not in CKs from Utah."