After a few calls to my landlord, a pest control guy showed up today with a can of spray as big as my head to kill the wasps. He sprayed the balcony, both top and bottom, and removed the nests. Thank goodness!
And just in case you were wondering, if you ever get stung by a wasp, you should scrape the stinger out with a butter knife. I know! When Oma came over and told me that, I said, "A butter knife?"
"I printed off directions from the internet."
"The internet! It's fine."
I grimaced. But hey, it worked.