This blog is intended to go along with Population: An Introduction to Concepts and Issues, by John R. Weeks, published by Cengage Learning. The latest edition is the 12th (it came out in 2015), but this blog is meant to complement any edition of the book by showing the way in which demographic issues are regularly in the news.

If you are a user of my textbook and would like to suggest a blog post idea, please email me at:

Thursday, February 20, 2014

Save the Monarchs--Plant Milkweed!

One of the most read items from the New York Times over the past few days has been the story about the threat to Monarch butterflies:
Hoping to focus attention on the plight of the monarch butterfly at a North American summit meeting next week, a group of prominent scientists and writers urged the leaders of Mexico, the United States and Canada to commit to restoring the habitat that supports the insect’s extraordinary migration across the continent.
Calling the situation facing the butterfly “grim,” the group issued a letter that outlined a proposal to plant milkweed, the monarch caterpillar’s only food source, along its migratory route in Canada and the United States.
Milkweed has been disappearing from American fields over the past decade as farmers have switched to genetically modified corn and soybeans that are resistant to the herbicide glyphosate that kills other plants. At the same time, subsidies to produce corn for ethanol have increased, expanding the amount of land planted with corn by an estimated 25 percent since 2007.
A year ago, before knowing about this potential disaster, my wife and I planted milkweed throughout our backyard to encourage Monarch butterflies. Our experience was a classic case of "plant it and they will come." The female butterflies lay their eggs on the leaves of the milkweed and then the resulting caterpillar eats much of the plant as it (the caterpillar) grows in size. It then leaves the plant to form a chrysalis on a wall or leave or chair leg (many options seem to be available) from which the butterfly emerges (see photo below from our backyard). It is a true miracle of nature, and the idea that trying to grow more food for more people should endanger this species is too much to bear, especially when there is an easy remedy--plant more milkweed!


  1. so what I hear you saying ... is that this worked? I actually have some milkweed seeds in a refrigerator (storage). been meaning to plant them. guess I will try it this Spring :-) Pete, Los Angeles