Monarchs are especially noted for their lengthy annual migration. In North America they make massive southward migrations starting in August until the first frost. A northward migration takes place in the spring. The monarch is the only butterfly that migrates both north and south as the birds do on a regular basis. But no single individual makes the entire round trip. Female monarchs deposit eggs for the next generation during these migrations.
By the end of October, the population east of the Rocky Mountains migrates to the sanctuaries of the Mariposa Monarca Biosphere Reserve within the Trans-Mexican Volcanic Belt pine-oak forests in the Mexican states of Michoacan and Mexico. The western population overwinters in various sites in central coastal and southern California, United States, notably in Pacific Grove and Santa Cruz.
The length of these journeys exceeds the normal lifespan of most monarchs, which is less than two months for butterflies born in early summer. The last generation of the summer enters into a non-reproductive phase known as diapause and may live seven months or more. During diapause, butterflies fly to one of many overwintering sites. The generation that overwinters generally does not reproduce until it leaves the overwintering site sometime in February and March.
It is thought that the overwinter population of those east of the Rockies may reach as far north as Texas and Oklahoma during the spring migration. It is the second, third and fourth generations that return to their northern locations in the United States and Canada in the spring. How the species manages to return to the same overwintering spots over a gap of several generations is still a subject of research; the flight patterns appear to be inherited, based on a combination of the position of the sun in the sky and a time-compensated Sun compass that depends upon a circadian clock that is based in their antennae.
-taken from wikipedia
The above paragraph basically means that the monarch butterflies make the whole migration trip over a span of four generations. How amazing is that?! It's like telling your great-grandson to return to his roots by leaving a message passed from generation to generation. The butterflies are way more amazing in that the message is imprinted in their dna. How they read/decipher it is a mystery though. Maybe there's a heavenly voice that speaks into their head all the time. *imagining a raspy voice saying "you must go north....cough..north...."* =_=
p.s. i'm smelling bacon from my neighbors. and currently the time is 12 midnight. what a delicious smell but at the wrong time. frustrating.
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