In the February 15/22, 2021 issue of The New Yorker there is a photo essay by Brendan George Ko of the annual migration of monarch butterflies, with accompanying text by Carolyn Kormann.
The butterflies have never seen the forest before, but they know—perhaps through an inner compass—that this is where they belong. an inner compass—that this is where they belong. They leave Canada and the northeastern United States in late summer and fly for two months, as far as three thousand miles south and west across the continent. The migration is accomplished in a single generation that lives eight months, whereas the return journey north will occur over some four generations, each living four to five weeks. This is the most evolutionarily advanced migration of any known butterfly, perhaps of any known insect.