Dasymutilla occidentalis, a “Velvet Ant” also known as the “Cow Killer” due to the severity of its sting, is actually a wasp. This is one of the wingless females.
I had significant trouble keeping up with her, as she was fully aware of my presence and not particularly pleased. Taking off my lens hood allowed me to get closer without spooking her, but she did her best to avoid the lens.
Most shots were too blurry, even at f/2.8 with my 60mm macro; anything under 1/1000 sec shutter was definitely no good, but luckily ISO 400 on the 30D is nice and clean. Depth of field was, of course, a major issue; look at this middle shot, where the eyes were the intended focal point, yet I just missed and focused on the back of the head. Uncooperative subjects can be frustrating.
I understand why ring flashes come in handy. Tracking this girl with a tripod would be impossible.
These wasps are parasites, and take over bumble bee nests and the like. I found myself in much peril chasing her across this patch of yard, as her hosts were more mobile even than she.