I was actually looking for an old photo of a black widow on my arm, for my dad, but I couldn't find it. Here's a photo of a male Arizona bark scorpion, Centruroides sculpturatus, instead. His name was Az. Females of this species have much shorter "tails". This isn't the best quality photo by a long shot, but it makes a good size comparison of the species against an adult human male hand. Formerly Centruroides exilicauda, and before that it was Centruroides sculpturatus, it's now gone back to the original C. sculpturatus name. The reason? The Baja California variety turned out to be a distinct new species, so it kept the newer C. exilicauda name and the original Arizona bark scorpion went back to the original Centruroides sculpturatus name.