As Lin said, they are attracted to colorful flowers & fruit. I found the info. below on a butterfly site:
You will also need to have some color, preferably yellow, purple, red or green, on the feeder because butterflies find their food by sight.
I am a strong believer in the simple fact is that what matters in this life is how we treat others. I think that's what living is all about. Not what I've done in my life but how I've treated others. ~~ Sharon Brown