Here's a great article by the NY Times about saving the Monarch migration:
http://www.nytimes.com/2014/11...
Honestly, I've been thinking about this for a while, and this article has kind of spurred me on, but I think I'm going to get rid of my tropical milkweed. You know I'm a native plant supporter and I don't want to be a hypocrite or hurt the Monarchs. I gathered some wild milkweed seed from KY this fall (not sure what kind, but one of the natives). We'll see how that does here and I'll go hunt down some native FL species, too. The trick is keeping the caterpillars off of it long enough for it to get established! I learned that the hard way.