It's a Wasp Eat Caterpillar World

I thought this wasp seemed to be flying a little oddly, so I followed her to her landing point, and sure enough, she was carrying something. I didn't see her nest, unfortunately.

Edit: I asked about this on bugguide (naturally), and it's a Polistes dominula aka the European Paper wasp. The adults drink nectar, but they feed chewed up caterpillars to their young.