Linsey - I don't have a butterfly feeder because it would probably attract too many wasps. A screen bird feeder like this one would be great for placing fruit in to attract some species of butterflies:
Not sure if any of y'all are members of Dave's...if so, I have a nice selection of photos of fruit feasters...butterflies that feed on butterfly brew, rotting fruit and other stuff like cow poo, scat, owl upchuck etc.
I got the new issue of Garden Gate in the mail today. In it, they have a recipe for butterfly nectar that looks like a very healthy nectar:
Stir a 20 oz. sports drink (Vitaminwater is good)and 2 cups of white cane sugar together in a pan. Bring mix to a boil and remove it from the heat. After it cools, add 2 Tablespoons of regular soy sauce. (The amino acids and enzymes in soy sauce help keep butterflies healthy.) Serve immediately. Store left-overs in refrigerator for up to 3 months.