Leucospis affinis Say, 1824. I had always assumed that because the ovipositor projected over the back that she would raise the abdomen and insert eggs with a upward tilted position, but your pictures show intriguing behavior that I never would have expected! great shots! Still don't know how she lays her eggs though.

Though I never observed them oviposit, Jim Hogue has told me that he saw them drilling through wood of nesting boxes in his yard. Also, there are some descriptions of the mode of oviposition in the literature. I just finished including a reference with one of the other images:

I've seen numerous wasps ovipositing, and this wasp was, from what I could tell, trying to oviposit. But I think it had a "exoskeleton/wardrobe malfunction" where the abdomen connects to the segment just before the thorax. In the image you commented on (above), what I've been referring to as its "innards", are somewhat hidden behind the right wing, however, in this image you can see, fairly easily, what appear to be the wasp's "innards" extending from the 'disconnected' first segment of the abdomen. You can even see what appears to be the 'inner' ovipositor (perhaps pulled out of the abdominal shell) lying atop the abdominal sack (for lack of the correct term).

Regarding your comment on the other image, "about to move the ovipositor into action, from the slung-over-the-shoulder position": every time she tried to move the ovipositor into action, it extended only as far as you noted. It never did fully extend or make contact with any surface. And each time she was done going through the motions, she'd pull the external shell back up, over that sack of abdominal parts (wish I knew the terms of all these things, so that what I'm saying made better sense).

However, be that the bother, what I'm most curious about is whether or not that exposure of the wasp's innards is a "normal" thing.

:-P)

PS - Yes, this is an active bee box. I drilled and hung out several of them last winter, and I've been watching steadily as bees and wasps slowly took up residence this spring. All four are currently about 95% full. Amazing how many different visitors come to it, both to move in and to pillage the residents.