Every fall, spectacular orange and black clouds of monarch butterflies fill the skies as they migrate from across North America to Central Mexico. West Coast populations make a similar though much shorter trip to coastal California. The National Wildlife Federation calls the monarch migration “one of the greatest natural phenomena in the insect world.” Not long ago, monarchs numbered in the billions, but in the last 20 years their population has dropped by 90%, due to habitat loss from pesticides, modern farming practices, urban development and other human activity. An estimated one million acres of habitat are lost each year.