She weighs less than .02 of an ounce.  Months earlier, her mother had left her as a tiny dot of an egg on a milkweed leaf in Ontario, Canada.  Now, 2,800 miles from where she was born, she is here in Mexico thinking about flying north.

She knows nothing of the metamorphosis that made her or how she made this incredible odyssey to the mountaintops of central Mexico.  But she is thinking of heading back north. She does not know that on her journey she will never reach the land of her birth. But she feels the urge to mate and fly away.

Only 750 miles northward into Texas, she, as her mother had done before in Ontario, leaves dots of eggs on a milkweed and dies.  She will not know that only her great or great-great granddaughter will have a chance to taste the nectar in the place of her own birth.

How this tiny creature, generations removed from any prior migrant, was able to navigate the long journey from Canada to the same clumps of trees in the mountains of Mexico where her ancestors had wintered, is one of the most amazing stories in all of nature…