Monarch Migration

by Wizzie Brown

I’m sure that many of you know about the migration of monarch butterflies, but for those of you who do not, or anyone who needs a refresher… Monarchs spend the winter in roosting spots. Those from west of the Rocky Mountains fly to areas along the California coast, while those east of the Rocky Mountains fly south to forests in the mountains of Mexico. This is a two way migration that happens in spring and fall, but monarch butterflies that fly north in spring are not the same butterflies that return in the fall. The butterflies that fly south in the fall, are the spring butterflies’ children’s grandchildren!

Not only are there two major migratory populations of monarchs in the U.S., there may also be a population that overwinters in South Florida. A biologist at the University of Florida recently discovered that a non-migratory population of monarchs in South Florida also contained monarch butterflies from the Midwest and Texas. She discovered this using a technique called stable isotope analysis which looks at chemicals that are fixed in the monarch’s wings as the wings develop and can therefore be tracked to plants fed upon as caterpillars. This paper suggests that monarchs may be overwintering in locations other than Mexico and California.

Many people want to know how they can help the monarch population, as there are numerous news reports on how populations are declining. One way that most likely will NOT work is rearing monarch butterflies to release into the wild. Researchers have found that monarchs raised in captivity are unable to orient for migratory purposes. Also, some monarch researchers are against the practice of releasing captive bred monarchs into wild populations for fear of disease transmission and the possibility of genetic effects when captive-bred butterflies mate with wild populations. You can read their statement here, https://monarchlab.org/images/uploads/attachments/Captive_Breeding_and_Releasing_Monarchs_oct2015.pdf

What can we do to help wild monarch populations?
Plant NATIVE milkweed and a pollinator garden. While spring monarch populations rely on milkweed to lay eggs and rear young, fall populations rely on nectar plants to provide energy for the journey south.
Use an IPM approach for managing pests in your environment.
Become a citizen scientist. There are numerous organizations that track monarch butterflies, such as Monarch Watch and Journey North.

Want to know more? Go to this site for more information on Texas monarchs and milkweed http://texasento.net/dplex.htm.

For more information or help with identification, contact Wizzie Brown, Texas A&M AgriLife Extension Service Program Specialist at 512.854.9600. Check out my blog at www.urban-ipm.blogspot.com

The information given herein is for educational purposes only. Reference to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement by Texas A&M AgriLife Extension Service Extension or the Texas A&M AgriLife Research is implied.The Texas A&M AgriLife Extension Service provides equal access in its programs, activities, education and employment, without regard to race, color, sex, religion, national origin, disability, age, genetic information, veteran status, sexual orientation or gender identity.