Alien Empire
Monarch Butterfly Migration

Monarch butterflies have one of the world’s most fascinating migration paths. Every fall, thousands of the black-and-orange butterflies fly west to their wintering grounds in California and Mexico, covering the trees there with their bright shimmering wings. The remarkable sight attracts scores of tourists: Pacific Grove, CA, has earned the nickname “Butterfly Town, U.S.A.” for the host of Monarchs that gather there every year. Come spring, the butterflies fly back to their summer homes, where they will lay eggs and die. A typical butterfly will make just one round trip during its lifetime.

For centuries, people puzzled over exactly where the millions of Monarchs that spend their winters in Mexico and California came from. But in 1937, a researcher named F. A. Urquhart began putting wing tags on the butterflies, allowing him to track some of the travelers. In the 1950s, he expanded the project, enlisting more than 3,000 volunteers across the country in his Insect Migration Association. For more than 20 years, the volunteers helped track the marked insects, contacting Urquhart whenever they found or saw a marked Monarch.

The results of the tracking project astounded many people. One tagged butterfly was tracked along a 1,870-mile route. Originally tagged on September 18, 1957 in Highland Creek, Ontario, it was spotted again in San Luis Potosi, Mexico, four months later. Of course, the butterfly’s actual flight distance was even longer than a map suggests, because the insects don’t fly in a straight line. They must dodge mountains, fight against winds, and flee predators on their perilous journeys.

Today, thousands of people continue to tag monarchs in an effort to study their migration. In 1997, for instance, the research organization Monarch Watch helped volunteers place small sticky wing tags on more than 75,000 butterflies. And in 1998, it distributed more than 200,000 tags to people interested in helping out with the annual tracking project. While the group isn’t sure how many of the 1998 tags actually made it onto butterflies’ wings, at least 35 marked monarchs were spotted at their wintering grounds in Mexico. One had flown at least 1,844 miles southwest from where it was tagged in Campbell, MN, to its roosting spot in El Rosario, Mexico. But some tagged monarchs took off in unexpected directions. One butterfly flew about 550 miles due west from western Kentucky to Lindsborg, KS, where trackers Grant Linder and Hannah Giles spotted it.

  • Michael

    Facinating program…Very good…

  • Paul Randall

    Interesting video. It says the females of the generation that flies from Mexico to the US lay 300 to 400 eggs. Assuming that same for subsequent generations, for each original pair, a total of perhaps 8.1 billion eggs will have been laid. To keep from overpopulating the world in just a few years, on average, only two out of every 300 eggs can survive to reproduce. I would like to have seen some information on the survival rates of each of the generations, and especially the ratio of number that start the migration south to the number that start the migration north. I would also like to have seen information on how non-migrating Monarchs survive winter in the US and perhaps a map of their habitat.

  • Karlin

    While watching this program, I felt like I wanted to go from Canada [where I live] to the Monarch wintering area in Mexico, and be re-born, free of my illness.

    It was a lovely thought – does anyone want to sponser me? :)

  • Meredith

    What a marvelous program!! I remember seeing the butterflies at Point Pelee Canada as a girl, and it was just as inspiring then as it is now.

    But I have a question: is there some difference between generation 1, and 4? Is there anything that defines a difference between the “one-month” butterflies and the fourth generation?

    Thankx for the GREAT show!

  • Gerry

    Thank heavens for programming like this! My wife and I thoroughly enjoyed the program and learned so much.

  • david leafloor

    Watch the butterfly program last night and was totally amazed at their migration. Am going to Mexico next month and hope to get to the migation site.

  • margot banescu

    being from ontario canada I never knew the migration of monarch butterfly was so amazing.Thank you pbs

  • Ruth Wallin

    Watched the program on Friday night and it was totally amazing. Why does it take 1 generation to travel 2,000 to Mexico, yet it takes 4 generations to return to Canada? I am mystified!

  • Christie M

    I very much enjoyed this program. I love Butterflies & learned alot of information that I didn’t know. ;)

  • Barbara Frank

    I missed the Monarch Butterfly Migration program and would it be possible to get a copy or is it going to be on TV again?

  • Keke

    I Love this butterflies!!!!!!!!!!1

  • Skeptigirl

    Your article says:
    “A typical butterfly will make just one round trip during its lifetime.”
    This is not correct according to other information sources on Monarch butterflies. Rather than one round trip, it takes 4 life cycles to make the annual round trip. 3 generations migrate north and the 4th returns all the way south, hibernates for the winter then begins the northward journey in the Spring.

  • Zandeleigh

    The monarch butterfly is sometimes called the “milkweed butterfly” because its larvae eat the plant. In fact, milkweed is the only thing the larvae can eat! If you’d like to attract monarchs to your garden, you can try planting milkweed. I deem the monarchs to be the most pulchritudinous butterfly of them all. May the wings of the butterfly kiss the sun And find your shoulder to light on, To bring you luck, happiness and riches Today, tomorrow and beyond.✿✿✿ -Zandeleigh✿

  • aurel min malang 1

    the monarch butterfly is very best,i like this

  • Jane Warner Lantz

    I have loved the Monarch butterfly since I was very young. They were plentiful here in the Midwest back then or so it seemed. My daughter-in-law let me know this was on tonight. Thanks to her I got to see my favorites on the wing. I thoroughly enjoyed it! A few years back, I saw a group? flock? of Monarchs on the sand of a riverbank in the Carolinas – very impressive sight!

  • Lindy Blanchard

    Who would of thought that butterflies could be so intelligent, so miraculous! Should give us humans courage to carry on through all our storms.

  • J

    Good information, it’s amazing how far the butterflies travel in a year. I enjoy observing Monarch’s in nature. Thank you for an informative article.

  • Bishop Andrew Gentry

    this may sound like a crazy idea but since illegal logging is posing a threat to the monarch butterflies in Mexico why not develop a type of , for want of a better term, “artificial warming poles” which would attract the butterflies. They could be powered by solar energy and would give off the heat the butterflies need to survive the winter. Just a thought.

  • Nature nut

    Does anyone know if a permit is necessary to tag monarch butterflies?

  • hannah

    why dont yall put more info on here

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