On some kind of elm (208838636).
I saw an ant (208838640) moving strangely and when I got a better look, the reason became obvious.
I'd read that not many species prey on ants, so I expected an ant specialist. Nope! Or, maybe somewhat yes! Ever helpful, The Bug Lady quotes Kansas School Emporium’s Checklist of Kansas Crab Spiders on Tmarus spiders eating ants.
It was not happy to have its meal threatened. It moved a couple of times when I stopped to check photo quality, and would have been more difficult to find except that the ant gave it away.

Perched on a post looking for food, then hopped down into the grass and caught a lizard. It carried the lizard and stopped in a few places bowing and making the downward low call.
Very cool to be able to watch this fellow for a few minutes.