I think I found a site made especially for you, Angelic. ^_^

Here's an associated content article quite literally about what you're looking for:
http://www.associatedcontent.com/art...tterflies.html

Another thing you MAY want to try (and don't hold me to this), are liquid vitamin supplements. I have a friend who swears by dropping a little bit into the soil to enrich the flowers. . . which I'm guessing may have an effect on how the butterflies sense them. I think she used silver water (I provided a link to the site) and a few other supplements.

Hope this helps!