Danaus Plexippus - The Monarch Butterfly
Note the lack of the third line on the lower wings, which Viceroys have. Monarch butterflies are famous for their yearly migration south, ending with forests filled with over-wintering butterflies hanging from trees. This migration actually takes several generations of butterfly to complete - it’s not just one set of individuals flying the entire distance. The fact that milkweed plants are endemic all the way from Mexico to Canada makes this feat possible.
No other butterflies are known to make a North-South annual migration like birds do.
American Entomology: A Description of the Insects of North America. Thomas Say, 1859.