Thank you Josephine! On one of the other threads Jay posted a link which depicts which Bidens species are native in any given state.
http://bonap.net/NAPA/TaxonMap...
I can provide you with B. pilosa seeds if you like. That offer goes to anyone who wants B. pilosa seeds.
Melanie, we see the swallowtails on them here but they don't really seem to light on them for long; they tend to do more of a fluttering wings, hovering type thing.