WSW: The Path of the Monarch Butterfly

Feb 26, 2014

Cluster of monarch butterflies in Santa Cruz, California
Cluster of monarch butterflies in Santa Cruz, California
Credit Brocken Inaglory, Wikicommons

Western Michigan University Biological Sciences Professor Stephen Malcolm says the population of the monarch butterfly in North America has dropped over the last 20 years. 

Malcolm was among a group of scientists that signed a letter delivered to President Obama, Mexican President Enrique Pena Nieto and Canadian Prime Minister Stephen Harper. It outlined the problems which have led to a drop of the monarch, especially east of the Rocky Mountains (Christian Science Monitor story). Malcolm says severe changes in weather and farming practices are among the reasons that fewer monarch butterflies have migrated between Canada and Mexico through the United States. He says the population decline has been even greater recently. 

The United States, Mexico and Canada have agreed to appoint a task force to study how to stop the decline of monarch butterflies in North America (NPR's Tell Me More on the summit). Malcolm calls that "encouraging." 

Malcolm says current agriculture policies in the United States and Canada encourage more growing of corn, he says a lot of that corn is genetically modified to be resistant to herbicides. But among the weeds that are killed by those herbicides is milkweed, where monarch butterflies lay their eggs (Los Angeles Times story). Malcolm says the monarchs are flying through an environment "saturated with various kinds of pesticides." 

The letter, signed by Malcolm and others, calls for more diverse roadsides. He says that could include allowing more weeds to grow. For instance mowing could be delayed until the fall. Malcolm says tougher regulations on growing genetically modified crops would also help the monarch butterfly make its way through North America. 

"They aren't just pretty butterflies, this is serious, this is real. These are real impacts and this is a great indicator species."

Malcolm says the monarch butterfly is "surprisingly informative" about the condition of our environment. He says studying monarchs also reveals information about food supply. Malcolm says "they aren't just pretty butterflies, this is serious, this is real. These are real impacts and this is a great indicator species."

If the decline in population can't be addressed, Malcolm says it could mean that the migration of monarch butterflies will collapse. He says the butterfly won't be extinct. But Malcolm says it's possible that the monarch migration which has been studied extensively in Michigan and other states won't happen anymore.