The Michigan DNR page on Monarch Butterfly (Danaus plexippus) says:
Often called the Milkweed Butterfly, this large black veined orange winged butterfly can be observed feeding on milkweed. During its mating behavior, the adult male monarch will display a “courtship dance.” Perching on the tips of the milkweed, it will fly to other large butterflies to see if one is a female monarch; if it is, they will fly together in a fast, darting flight, lasting up to a minute and covering many yards and to a height of 100 feet.
As fall approaches, the monarchs can be seen in large numbers migrating along the Great Lakes shorelines enroute to Mexico and Central America.
Monarch butterfly populations have been declining in Michigan for the last decade, and it appears that last winter was another tough blow for this beleaguered beauty. You can learn a lot more about Monarch butterflies and how to help protect them at Monarch Watch.