Prolepsis tristis. A genus with a single member in North America. And a highly impressive one. When I first saw a pair of these fly up I thought they were wasps linked in sexual union. Though, in fact, I had never seen wasp sex at that time. I was excited either way (yes, I admit that I am unusual). They were mating Prolepsis. These two in the picture are not mating. In fact, they are both males. The male on the left, which is apparently an orange-tipped color form, is eating the male on the right, the black-tipped color form. The female is even more wasp-like. And without any knowledge I would have passed these off on a past summer walk as wasps.

Side view, same pair of males, showing the fine color patterning on the orange-tipped form.

A specimen shot of the female who is indeed very waspish. Note the lack of the terminal hairiness and those striking red and yellow bands.

The females are much less common. On this day we saw four females and over fifteen males. The males were all cruising low over vegetation along the Arkansas river at the sand boundaries. It was an odd, sustained flight where they were either looking for mates or searching for food in a very unusual manner. Norm found this pair in copula. And I gave chase. Note that this female has much darker markings than the above. The male (attached) was a white-tipped form. We saw orange-tipped, black-tipped and white-tipped males on this day. The females in flight are one of the finest wasp mimics in the insect world for my money.

Here is a female series from Greg Lasley.

Norm's glowing female cocked oddly onto the middle legs but showing fine colors.