For some reason, the paper wasps have been extremely attracted to the greenhouse plastic covering my raised vegetable beds. I didn't see many wasps in the yard last year, but I'm reading their return as a good omen. Many wasps are beneficial predators in the garden and they're necessary for a healthy ecosystem.
You can get quite close to paper wasps without provoking aggressive behavior. I took this photo with an iPhone, which means I was no more than 12 inches away from it. Having said all that, I should probably stop putting my camera in their little faces. It's just not a great idea. (That goes for the bees, too, I suppose.)
I'm not sure what's attracting them to the hoops, though! It's a mystery... My working theory is that they're mistaking the greenhouse plastic for paper, which they use to make nests. (Hence the name paper wasp.)