One of the greatest migrations of the Animal Kingdom is that of the humble Monarch Butterfly. The Butterflies fly north from Central Mexico across the US and Southern Canada over three generations. The fourth generation turns around and heads south back to Mexico where they spend the winter in a very small area of the Michoacan state of Central Mexico before the whole thing starts again.
Every year, from November to March, betwen 60 million and 1 billion butterflies cover the trees of a few valleys only a few hours from Mexico City.
Mexico Trip.

see my other butterfly at:[ https://pbase.com/tomsview/butterfly
Mexico Trip.