BIOGEOGRAPHY OF MONARCHS

[mariposa]

I believe my question was already posted but I didn't recieve much of a
response - so I'm trying again.

I'm writing a paper about the biogeography of Danaus plexippus.  I looked
through Milkweed Butterflies but found it extremely technical.  I'm looking
for info about fossils, when they began to moved north, why, and when they
established themselves in Australia, Europe, etc.

I have a NON-science background.  Any info would be appreciated.

Thank you
mariposa at cwix.com