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: john.weeks@sdsu.edu

Sunday, March 8, 2015

Save the Butterflies--Plant Milkweed

Perhaps the only insects that humans love are butterflies, especially the magnificently beautiful Monarch butterfly. But the modern world of population growth and industrial agriculture needed to grow food for that population has inadvertently been wiping out the butterfly population by destroying the one plant in the world that Monarch caterpillars require to grow into a butterfly--milkweed. The National Wildlife Federation posted a useful story yesterday about six ways to save the butterflies, and generated this alarming set of estimates of the Monarch butterfly depopulation:



Now, to be sure, these numbers are based on wintering in Mexico. Where I live here in southern California, we have Monarchs year-round because, I assume, they don't need to go to Mexico to winter.  There are really two important things to do for Monarchs, as I have noted before: (1) plant milkweed; and (2) don't spray insecticides around your yard, because that will kill the eggs and caterpillars. If you have ants, as we do, just use those ant stakes you can buy at the store. They deal with the ants, but don't harm the butterflies. For more on this, take a look at a very good commentary from a midwestern farmer that aired this morning on CBS Sunday Morning. Our experience is that the butterflies reward you not only with their beauty, but their friendliness. They really do seem to love humans and will join you in the yard as you make life better for them.

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