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Polistes
They look like wasps? Very frighting to look up and see above your head.
Please consider adding this spotting to the Animal Architecture mission at http://www.projectnoah.org/missions/8082...
These are adult paper wasps of some kind. Wasps don't have nymphs, they have grub like larva which live in the chambers of the hive. You can also tell they are adult insects because nymphs are characteristically wingless. Many of these paper wasps are very similar so I'd may be a little tricky.
http://bugguide.net/node/view/572