Each year tens of millions of the fragile insects make the 3,000-mile voyage south, fluttering down the Mississippi valley, across the plains of Texas and over Mexico's rugged Sierra Madre mountain range to winter in central Michoacan state, where they carpet thousands of pine trees with a blaze of black and orange.
This year the pilot Vico Gutierrez accompanied them on their journey in his ultra-light aircraft named Papalotzin, a word borrowed from the ancient Nahuatl language of the Aztecs that roughly translates as "small butterfly". The aim of the trip was to draw attention to their odyssey, which is regarded as one of the most spectacular migration journeys in nature, and highlight the need for conservation.
Flying in small hops of 60 to 70 miles a day, the Mexican pilot said he stayed out of the swirling cloud of butterflies during their journey, but landed close to their roosts at night. He finally touched down on a remote road near the town of Angangueo on Thursday, to be welcomed by cheering schoolchildren wearing black and orange butterfly wings.
Mr Gutierrez said: "We need to put in place conservation projects, not just for the butterflies but also for the forests, the deserts, the oceans, rivers, plants and animals, and we need this to happen so, so urgently."
The Papalotzin team plans to make a documentary using film and photographs along the migration route.Reuse content