A Monarch Butterfly reserve is visited during the time the butterflies hibernate in the high altitude fir forests of the state of Mexico. The butterflies, seeking warm weather, arrive from the eastern side of Canada and USA during the last days of October and depart by March 21st. Riders can see them hanging by the millions on the fir trees. This is considered one of the most intriguing and fascinating natural migrations of the world.
Millions of Monarchs arrive each year in November to the same sites called “Sanctuaries”. In March, after several months in hibernation, the butterflies become active and get ready to fly back to the north. They will mate and with their last energy reserves will depart from Mexico by March 21st. They will barely make half of the journey back north to the place from where they came. Most of them will lay their eggs on the milkweed plant that begins growing in the southern states of the USA. Once they lay the eggs, they will die.
With the beginning of spring, millions of eggs hatch on the milkweeds. The caterpillars eat the leaves of this plant and take advantage of a chemical that makes their bodies toxic to birds that would like to eat them. This new generation of Monarchs will continue flying and spreading in the eastern side of Canada and the United States. Generations of butterflies with an average life span of 4 weeks will continue reproducing throughout spring and summer until the special generation is born again. The butterflies born during September have a different and special destiny. This generation will have a long life of approximately six months. They will be called the Mathusalem generation. They will fly south looking for warmer latitudes in Mexico in order to escape from the cold winter. They will make the amazing journey to central Mexico, to the same mountains; the same fir trees from where their ancestors departed several generations ago.
The stunning and little understood annual migration of Monarch butterflies is still a mystery to human mankind. The same question continues to arise as to how they can find their way through more than 4,000 kilometers while encountering many obstacles and adverse climate when none of them have made this flight before.
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