Once a year, at the end of the summer, the mysterious Methuselah generation is born. These are the only butterflies that live up to nine months.
While in the north, they store nectar, not just milkweed, to fuel the journey. In August, they start their trek to a place neither they nor their parents (or grandparents) have ever been.
At night, they roost clustered in the tree trunks and branches and snuggle up tight to keep warm along the way to Mexico.
In early November, they start appearing in the oyamel fir forests near Mexico City with the sole purpose of mating before making the long trek back in March.
Since none of the monarch butterflies who start the journey/migration complete it. It is rather hard to imagine how this can be. Do they use the sun as a compass, follow the stars, use the poles or topographical landmarks and air currents. But how do they make it to the same place every year in multiple generations. It is a mystery for sure.