That's really interesting. I try to plant flowers that will attract butterflies, but I've never heard of making a 'butterfly feeder' with rotten fruit.
Thank you so much for that wonderful link!!! My brain-damaged daughter planted "butterfly pincushion" plants in my mom's yard and is so excited everytime a "customer" shows up. I will definitely print up the info from those links for her to use.
I don't follow any rules for planting a butterfly garden. I do let tons of Common milkweed plants survive so the Monarchs can feed on them. I do remember to have a pebble filled plant base filled with water for the butterflies though.