I found out that hornets and wasps are pretty much territorial. They don't like to set up house where the other already has.
When I went searching, I found you can buy these for about 7.00 at Walmart that inflate and deflate for seasonal use.
But I am a tight wad and don't have a way to drive to town so I just made one. You can get the full pattern here http://www.thriftyfun.com/Faux-Hornets-Nest.html.
Here is a general idea for you to ponder then look further if you want. It's easy for even the beginning crocheter.
And here are some links in case you want more evidence these work.