I guess a hornet
According to one source, this is a subspecies that's found in Orange, LA, Ventura and Santa Barbara counties. I'm sure they're outside these counties but haven't been reported.
Paper wasp. Probably Polistes exclamans, though that broad black line across the thorax is atypical.
http://bugguide.net/node/view/11641
Lat: 33.71, Long: -117.83
Spotted on May 13, 2012
Submitted on May 13, 2012