Monarchs are probably the most ubiquitous and recognizable of butterflies. What sets them apart from other butterflies is their unique and long migration. Those that spend the summer in the eastern two thirds of the U.S. and Canada fly to Mexico in the fall, a journey of a couple of thousand miles. They are gliders that ride on thermal winds and can average around 30 miles an hour. Some have been observed flying as high as a mile. It has yet to be determined how the monarchs can navigate and fly to 12,000 foot mountains where they have never before been, a place where their ancestors have ventured for millennia.
Spending the winter in the high mountains of central Mexico, millions upon millions of monarchs mate in the spring and the females fly north, to the U.S.to lay their eggs on milkweed plants. It takes two or three generations for the progeny of Monarchs that leave Mexico in the spring to reach the northern U.S. or eastern Canada. These summer mating monarchs live only about three weeks. The monarchs that emerge in September go into sexual diapause, store up on nectar and begin their long journey south. They live for about ten months. How they navigate and find their way is still unknown and is the subject of ongoing scientific research.
For more information on the Monarch lifecycle, go to Academy of Natural Sciences – Four Stages of Butterfly Metamorphosis.