"Are we almost there yet?"
"The butterfly that goes from Canada to Mexico and partway back lives six to nine months, but when it mates and lays eggs, it may have gotten only as far as Texas, and breeding butterflies live only about six weeks. So a daughter born on a Texas prairie goes on to lay an egg on a South Dakota highway divider that becomes a granddaughter. That leads to a great-granddaughter born in a Winnipeg backyard. Come autumn, how does she find her way back to the same grove in Mexico that sheltered her great-grandmother?
Wildebeest, in their famous migration across the Serengeti, learn by following their mothers — or aunts, if crocodiles get Mom. But the golden horde moving south through North America each fall is a throng of leaderless orphans.
Birds orient themselves by stars, landmarks or the earth's magnetism, and they, at least, have bird brains. What butterflies accomplish with the rudimentary ganglia filling their noggins is staggering."