These wasps are quite common again in late summer through to fall. You'll notice them in spring as well, then there is a hiatus before the second generation appears. As their name suggests, these wasps build pots in which to lay their eggs. They are beautifully crafted and many look very much like miniature clay pots a human might make. QUite ingenious. Here is a link to some potter wasp pots: http://www.pbase.com/laroseforest/image/136651015. Unfortunately, these were already beginning to crumble by the time I found them.