Mexico: Monarch Butterfly Migration in the Americas · Global Voices
Andrea Arzaba

Between Mexico, Northern United States, and Canada there is a very unique phenomenon that reminds many of how miraculous nature can be. This astonishing feat is made by the monarch butterflies, which are insects that span the life of three to four generations to get from one country to another.
Mariposa Monarca picture by flickr user Gustavo (lu7frb) and used under a Creative Commons license.
In the blog Destinos Inolvidables [es] (Unforgettable Destinations), monarch butterflies are described as:
La mariposa monarca, además de su gran belleza, se caracteriza por su resistencia y longevidad, pues mientras otras especies de mariposas tienen un ciclo vital de 24 días, la monarca llega a vivir hasta nueve meses, es decir 12 veces más.
The monarch butterfly, apart of its beauty, is characterized by its resistance and its longevity, while some other butterfly species have a life cycle of 24 days, a monarch butterfly can live up to 9 months, meaning 12 times longer.
Every year at the end of October, millions of monarch butterflies arrive to forests in Michoacan and the State of México in Mexico after flying approximately 4,000 km from the Northern US and Canada. Inhabitants of the region and tourists come to witness the large number of butterflies in the forest, in places known as  sanctuaries. At the blog Tips de Viajero [es] (Traveler's Tips), the experience of visiting a sanctuary is explained:
Un magnífico paseo, y bastante cansado, pero llegar a la cumbre y ser testigo del vuelo de millones de mariposas a tu alrededor, es indescriptible. Los niños se maravillan y los adultos recobramos la capacidad de asombro: no cabe duda que la naturaleza es sabia.
A magnificent trip, very tiring, but when you get to the top and you witness millions of butterflies flying around you, it is indescribable. Kids get amazed and the adults regain our capacity for astonishment: nature is wise, there is no doubt about it.
Video by DavidDJC84:
This event goes back to ancient times, as there exist admiration testimonies. Even in Mexican archaeological sites, sculptures and paintings of Monarch butterflies have been found. Sadly, because of deforestation and brutal weather changes, butterflies are finding it harder to survive. According to El Universal newspaper, in the beginning of February, 30% of the monarch butterflies in one of the most important national sanctuaries, Santuario Piedra Herrada [es], died from a strong cold front in the region.
However, this migration phenomenon continues strong today. One of the most typical festivities in Mexico is El día de los Muertos (Day of the Dead), it is when Mexicans commemorate the memory of their beloved ones that have passed on. An indigenous culture, the Mazahua people, believe that the arrival of monarch butterflies every October represent the souls of the dead, as they also believe they bring a message between the gods and the Earth.
In the blog Rojo Mariposa [es] (Red Butterfly) this incident is mentioned:
Además de ser considerada como un ser mágico en mi país, por llegar en las fechas en que según la tradición de Día de Muertos, llegan también las almas de los santos difuntos.
¿Ahora entienden por qué me fascina tanto esta maravilla?