Wasps

Does anyone know a great remedy for the swarms of wasps that have taken up residence in my backyard? Early this spring we noticed a nest in our shed, sprayed it with bug-killer and thought that would be the end of it. Over the last few months, we have continued to find new nests all the time. I think this is the current count.
6+ in or around the shed
6 under the railing of the deck
1 on the house
unknown number yet to be found (where else can they hide?!)
1 wasp sting - minor

Tonight The Man went to the store and bought four more cans of wasp-killer. He came home and promptly sprayed the recently discovered nests. I really appreciate him doing this since I don't do the icky bug/vermin thing. I appreciate it even more knowing that he is allergic to bee stings and is quite literally risking his life to rid our house of wasps. Thanks honey! Oh, and sorry to the neighbors who now have to put up with recently displaced flying needles.