About 5pm on a sunny day, I found this wasp circling around my chest in my driveway. I stood still as it circled lower to the ground until I spotted a paralyzed caterpillar it had probably dropped when I had crossed its path. I finally had a chance to photograph the wasp as it found and tried to pick up the caterpillar. Then, carrying the caterpillar, it proceeded to walk along the ground in a straight line across moss and litter for a dozen feet, changed direction 30 degrees crossing a brick path, and then resumed the former direction. It put down the caterpillar and hunted in circles along the ground until it found a hole about a foot away. It entered the hole, tossed out a couple ants, came back and put the caterpillar in, came out, chased off some other ants and small hovering insects that could have been flies or wasps, took the caterpillar back out, put it in and out again, and finally took it out and carried it five feet up a nearby oak tree. It dropped the caterpillar, found it again, took it a foot up the same tree, dropped it again, found it again, and took it up to the top of a two foot azalea about three feet away and out to the end of a branch near a spent flower where the large caterpillar camouflaged perfectly. It flew off in circles until I lost track of it. I noticed that if the wasp had proceeded in its original direction instead of changing its direction at the brick walk, it would have reached a different hole the same diameter, in moss, on the other side of the oak tree. Perhaps that hole was its intended destination and it was stashing the caterpillar until it found the correct hole or dug another one. Fifteen minutes later when I returned to the azalea, the caterpillar was gone but both holes were open.
The wasp had white marks on sides and top of black thorax, and an irridescent blue abdomen The wings looked dark brown. The first joint of the legs was black or dark brown, then gray in many of the photos. Eremnophila aureonotata
looks very similar. By its behavior I assume the wasp is a female.
The caterpillar is of the moth Heterocampa guttivitta, Saddled Prominent.