That nest looks just like the one in the ceherzog, ID, Bald-faced Hornet Nest, Dolichovespula maculata. I was a little confused at first because it looks as if the nest was in the ground, but now that you clarify that it was hanging I believe ceherzog is right.
Nice spot. How big was it? Also, this is a good candidate for the Nests, hives, bowers, webs & other animal architecture mission. It can be found in the link provided.
http://www.projectnoah.org/missions/8082378
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