Identified by Josh Rose. Size of individual wasps estimated. They had a spherical (about 15 cm wide) nest in a dense shrub. These are eusocial wasps that make and store honey--see guide page. I gingerly pushed my camera in through the branches of the shrub to get a couple of shots and, luckily, did not get stung. They are said to be aggressive by some sources.

This is a new genus and species for BugGuide.