Great Black Wasp (Sphex pensylvanicus) 6/27/12 PL DE (see description)

Great Black Wasp (Sphex pensylvanicus) 6/27/12 PL DE (see description) Saw this fluttering about the patio door. Huge wasp. It was very restless so was afraid to open door for fear of driving it away. Only got one picture, sad as it is, and I contented myself with watching it for the short amount of time it was here.

Desperate for field marks, I couldn't see any, just a plain black wasp. There was one tiny ray of hope a bit later when it sat still for a couple of seconds and I saw faint, fading, light/white bars across the ventral side of the abdomen. Searching online and on BugGuide led me to think this might be the Cicada Killer, but I couldn't find any pictures to corroborate the striping I saw on the abdomen.

Later in the afternoon it stopped by again for a few seconds. This time I was outside. Maybe some day it will come again and stay a little longer.