Thanks for sack of rotting fruit!
I never would have thought to try this until I saw people on here posting about it. There have been a lot of red admirals around lately and so I thought I would try it for the first time since they supposedly like it. I grabbed some mushy apple and pear cores out of my compost bucket, threw them in a mesh bag, and hung it up. Within ten minutes there was a red admiral on it, and not long after this guy showed up. I had to get some photos to see if it was a comma or question mark. It was a question mark, the first of the year and not super common for me. It stayed there for a good half hour. I thought it might be stuck, but it wasn't. It was just really enjoying itself. So much so that I was able put my camera within two inches of it to get some photos.
So thank you all for the great idea. For anyone that hasn't tried rotting fruit yet... give it a try.