A Renewed Migration from Mexico
One of America's favorite imports from Mexico is butterflies, especially the 300 million to 400 million monarchs that each spring and summer flutter across much of the U.S. and as far north as Canada in search of cooler weather. This year's migration is especially sweet. A devastating cold snap in January 2002 was estimated to have killed 75% of the monarchs that winter in the Transvolcanic Mountains of central Mexico, about 90 miles west of Mexico City, where they have inspired a growing tourism business. Lepidopterists had been worried that the butterfly population wouldn't bounce back,...