I suspect these are Spider wasps which are in a different family (Pompilidae) from the several Sphecid wasp families. Confusingly, there are several genera of Hunting wasps or Sphecidae that all use spiders.  I can say these were small wasps. And notice the pale spider beneath the wasp on the right. These two wasps were having a kicking, banging, rollicking battle over this spider who was limp and had obviously already been paralyzed. You can see the wasp on the left is pulling on a spider leg in this shot. The right wasp has a different leg. It was a crazy chase on this stream bank with me running over them snapping shots as fast as I could.

Another spider wasp which is in the Pompilidae. This one has a paralyzed spider. Or had one. I surprised the little girl and she dropped it. She stood off for a distance waving those impressive antennae and then slowly worked her way back in a large arc until she tapped her antennae on the waiting victim again. I have about 120 estimated Pompilids for Arkansas. Less by far than the total of eastern Sphecids. Many of the spider wasps are dark-winged as this animal is. This may be Phanagenia (see below) but difficult from this angle.

This appeared to be a very striking Pompilid with a blue-purple abdomen. Large species. Twice the size of the above spider hunter. Taken in September. Several of the genera have metallic scaling and coloration.

Spider killer which is very likely in the group with the astounding Tarantula Hawk. The larger genus is Pepsis. Eric Eaton states this is likely an Entypus and very likely E. unifasciatus. Most species have some orange color in the wings. Also note those impressive matching antennae which these wasps flag around excessively when on the hunt. This particular lady was preening and mudding at a waterhole with many honey bees which she positively dwarfed in size (this wasp is three times the length of an Apis) but she never acted aggressively toward the bees.

Same wasp, forward view. She spent a great deal of time cleaning and preening after her drinking/mudding experience.

Spider wasps generally don't come in souped-up models or highly colored individuals except for some of the oranges and flashy metallic colors that you see above. So when I saw this wasp pulling something across the leaf litter I didn't even think it was a wasp. I thought it was a Yellow jacket, a Vespid. But then I could see it was tugging a big orb weaver with it. Further images and description.

Another souped-up model in an entirely different group. And an extremely interesting genus. This is Psorthaspis luctuosa. In a group with several orange and creamy marked species. This is a very small wasp in that group and has been located now in TX and in AR. Edward Trammel found some in north central Arkansas and I unearthed this one beneath a dead pine log in Faulkner county. Did not like to fly. (Edward's apparently didn't fly at all.) Very active thing. Hopped and dove into leaf litter rapidly.

And compare that with this significantly larger Psorthaspis female. This is the striking P. sanguinea. More widespread in the east but these are still not that common. She was hunting in my front yard. Actively tipping and digging into the bark and diving down into leaves. I have taken some male Psorthaspis in traps on the property and I think Nick Fensler thinks they were mariae. Image here. Males are odd as you can see. I have never seen a male in life outside a trap. We now have five specie of Psorthaspis in AR. I am still trying for a live shot of brimleyi.  

Spider wasp of the gargantuan size. With iridescent greens mostly and absolutely blaze orange wings. She was over 40mm long.  Found her hunting intently over one of the rocky ridges at Camp Robinson WDA. She would occasionally dig but never accomplished much. I think these Pepsis species make a kill before they dig or actually use the Tarantula hole itself for the burrow. It remains controversial on the species of Pepsis in Arkansas. (See the key here to most of the eastern and central species.) But the museum has P. angustimarginata (possibly wrong ID), elegans, mildei and grossa (previously formosa). I believe now from Banks 1921 key that elegans has black wings, orange antenna and mostly blue body iridescence. The true giants are grossa and mildei. P. mildei may be orange antennaed or partially orange-antennaed as well. P. grossa can have orange antenna tips. This big female has no orange at all. All species apparently only take Tarantulas which is remarkable in my area where I rarely see these big spiders.

Another Pepsis spider wasp with much less impressive orange in the wings and visible orange antenna tips. Wings were worn but darker distally. Still with the great green body iridescence. This is from my Eupatorium stand on Round Mountain. May again be grossa as I am not sure mildei would have this little orange in the antenna.

And a definite male Pepsis with the light coming through those electric orange wings. Excellent blue sheen on this one. Males notorious to identify by images. This is a July Pepsis which is fairly early in the summer for me to find these. This one was intensely nectaring on this plant for as long as I stayed.

And Tom's September Pepsis female also dark all the way to the tips of the antenna.

This was a rather large Pompilid in Johnson county. I could not be sure what species of spider this was as I did not handle the prey item. But it was later identified by G. B. Edwards as a juvenile Dolomedes. This is a known prey genus for atrox. Wasp size estimate was 24 to 26 mm. And this is the color pattern of several of the Anoplius species. Only a few would be this large. A. bengtsonni was possible but is supposed to have hairy femora. A. atrox apparently approached this size and is also marked with the orange spot. It was identified as atrox. Confirmed by Nick Fensler. Walked backwards with the hefty spider prey.

 

A close up shot of the above Spider wasp in the genus Anoplius showing the amount of hair on the head. This is a very good character for this large genus.

A top shot of another September Spider wasp which may also be a big member of the genus Anoplius. Hard to see hair on the head here. Several species, including the common amethystinus lack orange spotting on the abdomen and have various mixes of iridescence.

And another dark specimen in September 2013 on my wife's chive stand with manyother insects. Also likely Anoplius with the facial hairiness visible. Touch of red near the terminal abdomen.  

An October shot of a definite Phanagenia bombycina. Note the hind tibia that is not serrate. This was about a 14 mm wasp that disappeared into the leaf litter. This is a Lycosid spider and note that all the legs have been severed by the wasp. A few genera of wasps make a habit of this. This genus and Auplopus in our area are the notable ones. This is the only wasp in this genus in our state. It constructs mud nests often in rocky crevices.

Same wasp, frontal shot. You can see the palps of the spider extending forward with all the legs missing. It appeared to carry the prey by the base of these palps.

Stunning big Pompilid. This is Tachypompilus ferrugineus. Spotted her in my yard and then saw she had the paralyzed spider already sitting nearby. Sat and waited. She watched me. I watched her and eventually she came to claim this big Dolomedes from in front of me. She dragged it ten yards or more across the yard and I let her go on her way. 

Same girl. Dragged it backwards by the left palp.

And one nice Tachypomp from Craighead county near Norm's home. With a Rabidosa Wolf it appears.

 
And a different Tachypompilus ferrugineus in September 2013 on the chive stand in my yard. Excellent black sidewalls. And those long legs. One of my favorite wasps.