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Monarch Migration Update: May 3, 2000

Today's Report Includes:

Highlights From the Migration Trail
No sooner had we made this week's migration map, than this exciting news arrived:
  • Monarch Migration Map
    Spring, 2000

    While on a field trip yesterday in Adrian, Michigan, Madison Elementary 1st graders sighted the first monarch for their state. "We have been following the monarch migration all year. We were having lunch outside when we sited a monarch in the park!", they said.
  • Also yesterday, Kate Taylor reported a faded monarch in Blackwood, New Jersey. This suggests that some monarchs from Mexico are still alive--and have traveled some 2,100 miles from Mexico!
  • And here are another 30 sightings for your migration map. (See: This Week's Monarch Migration Data)

How Far North Do Mexican Monarchs Travel?
Your map probably now shows how far the monarchs from Mexico will travel this year. (Notice that the leading edge of the migration has reached about 41 N, all across the monarch's range.) As this generation dies, we expect to see a drop in sightings over the next weeks. After all, these butterflies have been alive for a long, long time! That's why we asked last week...

How Long Have These Monarchs Been Alive?
Discussion of Challenge Question #36

"Assume a butterfly emerged as an adult last August 26 in Maine. For how many days has the butterfly been alive as of April 26, 2000? For how many weeks?"

"Our class answer is that the monarch has been alive for 245 days, or 35 weeks," wrote Miss Bailey from Citrus Elementary School Vero Beach, FL. That's 8 months!

"We had fun with this one," she said. "Our second and third graders tried to add the number of days in each month to figure out how long the monarch had been alive. Then they tried to divide their answer by seven to get the number of weeks (that was more difficult, since they're still learning how to divide). They worked independently in their journals. Then they turned in their work. After that we worked it out together on the board. I told the kids we would submit the answers closest to what we worked out together. All the kids did a great job!"
Story of a Life's Journey
If a monarch butterfly could talk, just think of the stories it could tell! Imagine a butterfly whose life began 8 months ago in the north, and write its life story:
  • Describe all the places this imaginary monarch has been--the different habitats and biomes it has traveled through, the seasonal changes it has experienced, and the many changes its body has undergone.
  • Imagine all this butterfly has had to do to stay alive! What challenges has it had? Any narrow escapes? Where did it find food, water and shelter?
  • Imagine the different people this butterfly might have seen, and the languages it overheard. Maybe it's even looked down on people you know, who live in different states, provinces or countries! In what ways are people working to help the monarch butterfly?
  • What will happen next, now that its journey is over? How will the story continue, even though the butterfly's life is coming to an end?

Challenge Question #37
"Please share your stories with Journey North! We'd love to know what you and your imaginary butterfly have learned during this school year."

(To respond to this question, please follow the instructions below.)

Fading Away...After 245 days of life, it's no wonder the monarch Mr. Jim Edson found in Arkansas last week looked like this! The fading of the wings is caused by the loss of "scales" (tiny, dust-like particles that are found on wings of butterflies and moths).

Next Generation Soon on Its Way!
A New Way to Look at Your Migration Map

Last week we suggested a new way to view your map. If you assume that:
  • Eggs were laid at all the places where monarchs were sighted, and
  • It takes 32 days for a monarch to develop from an egg into an adult.

Challenge Question #34 asked, "What dates does your new legend show? What title would you give this new map?"

The "Migration" Map Becomes....

A New Map!
"Next Generation" Map

On the right is the new map! It shows when and where we can expect the next generation of monarchs to emerge. Note how the dates of the legends changed:

Monarchs Sighted
(Legend of "Migration" Map)

The Next Generation
Should Emerge
(Legend of "Next Generation" Map)

Before March 15

Before Apr. 16

Mar 15 - Mar 28

Apr. 16 - Apr. 29

Mar 29 - Apr 11

Apr 30 - May 13

Apr 12 - Apr 25

May 14 - May 27

Apr 26 - May 9

May 28 - Jun 10

Discussion of Challenge Question #35
Using the same assumptions, Challenge Question #35 asked, "When might we expect monarchs to emerge in Arkansas?"

Mrs. Dempsey's second grade class in Framingham, MA considered this question and decided they, "expect the monarchs in Arkansas to emerge on April 21." (

What a good estimate! If you look at Arkansas on the migration map, you'll see many light yellow dots. The legend says this means the first monarchs arrived there between Mar 15 and Mar 28. According to the new legend above, the first NEW monarchs to emerge should be between Apr. 16 and Apr. 29. So the April 21st estimate is right on.

And here's proof from Arkansas! Jim Edson's first monarch emerged on April 27th. "I released my first monarch that came from an egg that was laid March 27th," he said. "She was raised in a screened box that was kept outside." ( It took this monarch 31 days to develop.
Are the Monarchs Ahead of Their Milkweed?
Discussion of Challenge Question #33

Mrs. Dempsey's class also did a great job summarizing the milkweed observations reported from each state in our April 26th update. They noted:
  • Georgia--milkweed arrived first
  • Kansas --milkweed was ready when monarchs arrived
  • Virginia--milkweed emerged as monarchs arrived
  • New Jersey--monarchs arrived before milkweed was ready
  • Missouri--on April 11, no milkweed but was there any on the April 15? Probably the monarchs came before the milkweed was ready.
  • Arkansas--The reason why she laid so many eggs is because there were less or not as many emerging milkweed plants in the area so she saved up all her eggs for the plant in the lab.

As the students point out, many people have been seeing their first monarchs JUST as the milkweed is emerging. Now remember: When milkweed emerges it's only a tiny plant. It takes time for the plant to grow and for its first leaves to unfold. And when the eggs hatch only 3-5 days after they are laid, very hunger caterpillars will emerge--ready to eat the leaves. If you've ever raised a monarch, you know how much milkweed one larva can eat!

This is why monarchs typically lay only 1 or 2 eggs per milkweed plant. Last week, we saw examples of what's known as "egg-loading." (This is when many eggs are laid on a single milkweed plant.) In Georgia, Mark Barton reported 12 eggs on a single plant with only 6 leaves! And when trapped in Jim Edson's lab in Arkansas, the monarch laid 87 eggs on a few milkweed cuttings! If you observe egg-loading where you live, you have clear evidence that monarchs are not finding enough milkweed.

Which Grows Faster, a Monarch or a Milkweed Plant?
Here's an experiment you can try to get a better idea of how much milkweed an early monarch might need in the spring:

1) Watch for a milkweed plant to emerge this spring.

2) When its first leaves appear, measure the surface area of each leaf. (To do this, make a grid by photocopying graph paper onto a clear transparency. You'll be able to see through the grid and count the surface area on the leaf.)

3) On a sheet of paper, make two columns like this:
Date Surface Area of Milkweed Leaves

4) As the plant grows, record the amount of milkweed that's available each day.

5) Next capture a monarch larva, and measure how much milkweed the larva eats in the 9-14 days it takes to go from egg to chrysalis.

6) Then summarize your results:
  • How much milkweed can one larva consume in its days of eating?
  • How many days does it take for milkweed to grow enough plant material to meet one larva's needs?

Volunteers Needed!
Monarch Larval Monitoring Project
In order to monitor monarch populations, Dr. Karen Oberhauser and Michelle Prysby are looking for volunteers to collect long-term data on larval populations and milkweed habitat. Their overall goal is to learn how population densities fluctuate throughout the monarch breeding season in North America.

This is important information, because when conservation issues arise (such as the impact of Bt corn on monarchs), we see how little is really known about healthy monarch populations. If you'd like to help with this study, please see the Monarch Lab website for details.

Journey North
Year End Evaluation
Please share your thoughts

Please Note: We will continue to track the monarch migration until the butterflies reach the end of the road in late June. However, we're asking for your evaluation of our program now, before the end-of-the-school-year rush. Thank you!

The Next Monarch Migration Update Will Be Posted on May 10, 2000.

Copyright 2000 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to our feedback form

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