This bug landed on my hat with a loud thud. I must have heard him coming, because I looked up and saw him just a moment before I heard and felt him land. I removed my hat carefully and there he/she was. Although I'd never seen a wheel bug before, I knew what it was, and to be careful.

This bug was aggressive from the start. He immediately began to move towards my hands holding the hat. I put the hat down to take pictures of him and he moved to the point closest to me and faced directly at me - not much good for photographs. I used my monopod to bait him and turn him sideways. He always turned back to me eventually, but not before I got some shots. He never backed away or showed any fear of me - very unusual for an insect in my limited experience. In the second photo he's displaying his "intimidation" posture with his front legs spread wide to either side.