The amazing life cycle of the American Monarchs. If we are to reverse the appalling decline of these butterflies, it is helpful to understand more about of the remarkable life story of the American Monarch.
In the summertime, Eastern Monarchs can be found all the way from Mexico to southern Canada, and from the Rocky Mountains to the Eastern seaboard. All across this huge land area, four or sometimes five generations of Monarchs are born in a single season!
Starting in September and October, all Eastern Monarchs, (with the exception of a few that use the Atlantic seaboard) undertake a single prodigious migration to reach their over-wintering destination, the Monarch Butterfly Biosphere Reserve, in Southern Mexico.
During this migration, these tiny creatures fly the most astonishing distances. Those that begin their journey in the Canadian Maritime provinces will travel nearly five thousand miles to reach their winter destination in Central Mexico. Butterflies begin their fall migration in September or October, and finally reach their overwintering sanctuary in November.
The following March, those same butterflies set out on their northbound trip. However, no individual butterfly flies all the way north: At successive stops along the way, the female monarchs lay eggs on milkweed plants, and the resulting caterpillars initiate the new generation of butterflies that continue the journey northwards. It is estimated that in the course of the entire summer, eventually four or five generations will be raised.
In early fall, the final generation of females store their food supply in preparation for their long flight back to Mexico, instead of producing more eggs. These butterflies are also programmed to fly south or south-west depending on their starting points, to reach this single destination.
Like their eastern counterparts, the Western Monarch butterflies also have a migratory life cycle. Their summer territory is to the west of the Rocky Mountains, where typically, they will hatch three generations at successive points along those fly-ways.
Every fall, the third generation of these butterflies is programmed head south-west to reach one of several over-wintering destinations along the west coast of California and western Mexico.
Unlike the Eastern and Western populations, American Monarch butterflies that are found in Florida and along the Gulf Coast do not migrate. This minor population remains in this warm climate on a year-round basis.