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Monarch Butterfly Migration Update: May 16, 2001

Today's Report Includes:

First Spring Generation Spreads Across the North
The predicted population explosion has occurred! During the last week, 44 sightings were reported. And while this week's map was being made, more sightings poured in from Minnesota and Wisconsin. (If your monarch sighting missed this week's map, we'll be sure to include it next week.)

Monarchs are insects, you know. And if there's one thing insects can do quickly, it's reproduce. Of the hundreds and hundreds of eggs laid by each female monarch, many have now reached adulthood--and have continued the migration northward. Look how the jump in numbers occurred in May, after a typical lull in late April:
Week

# sightings

May 9 - May 15

44

May 2 - May 8

24

Apr 25 - May 1

19

Apr 18 - Apr 24

14

Apr 11 - Apr 17

18


People are noting fresh wings, and some people are seeing more than a single monarch. These are both good signs that the new generation is on the wing. This week's migration map shows where observers reported fresh, new monarchs. (We've also indicated "1st spring generation monarchs" on the data below for your own migration map.)

Please Help: YOUR Monarch Sightings Are Important!
Even if early monarchs have already been reported from your state or province, we want to hear from YOU! The number of sightings we receive reflects how abundant monarchs are, so your observations continue to be important.
Remember: Monarch Migration Updates Will Continue into June
Other Journey North migrations have come to an end, but we'll continue to track the monarchs until they reach the end of the migration trail, sometime in mid-June.
Do You Have Spring Photos of Monarchs to Share?
We have no pictures of monarchs on spring flowers! If you have photos you'd be willing to share, please contact us: our feedback form

We'd love to decorate these pages with your favorite monarch photos!
Highlights from Along the Migration Trail
Excited voiced called out from 17 states and provinces during the past week. Here are comments from some of the observers:

May 13 Minneapolis, MN
"The fifth graders at Annunciation School have been eagerly looking for their first monarch of the spring. We have been studying monarchs since last fall and are keeping our migration map updated on our bulletin board. Grace and her mother saw one (a fresh, new one) in their backyard garden. It was on a lilac bush. Peter saw one in his backyard and the wings appeared faded and slightly tattered. Observed for 15 sec. Lauren saw a monarch while playing softball and it flew in front of her face. She got a good look at it and the colors appeared bright."

May 14 Spencerport, NY
"Vanessa in Mr. Cardella's third grade class in Spencerport spotted a monarch while getting the mail. It was on her mailbox and had wings that were in good shape."

May 14 Chaska, MN
"I saw MY FIRST MONARCH OF THE SEASON fly past, then back, then all around us for about 15 minutes. I was with my two little friends (ages 8 and 5) who rear Monarchs with me all summer, so we were all ecstatic!"

May 15 Spicer, MN
"Two of my students, Alyssa and Tara, saw an adult, male monarch flying around a lilac bush Tuesday evening. When it landed, they were able to see the spots that told them it was a male."

A Look at the Life of a Monarch Caterpillar
Just moments after a monarch hatches from its egg it devours its own shell. A fitting beginning for a creature whose focus is FOOD!
Monarchs spend every day of the larval stage of their lives eating--and growing. In fact, the typical monarch increases in mass by 2,000 times while it's a caterpillar. This amazing transformation takes place in only about 9-14 days.
  • The weight a monarch gains as a larva determines the butterfly's size as an adult. Bigger caterpillars become bigger butterflies; smaller caterpillars become smaller adult monarchs.
  • Once a monarch becomes an adult butterfly, it does not grow any more.
  • As you know, the final monarch generation of summer migrates to Mexico. A butterfly's chance of surviving the winter is greater the more lipids it has stored. This means that the milkweed conditions available to larvae in the north can ultimately affect their chances of surviving the winter!

  • Larvae at each of the 5 instars
    Photo: Karen Oberhauser

     

    Photo: Jim Edson

    Larvae go through five growth stages called "instars." This is because, as insects grow, they must shed their exoskeletons as they increase in size. Just as children outgrow their clothes, insects outgrow their skeletons! (Luckily, human skeletons are inside our bodies and grow with us.)
  • In addition to eating and growing, larvae must avoid predators and parasites! Mortality is extremely high. Between 80- 90% of all eggs laid never survive to adulthood, according to results of the Monarch Larval Monitoring Project. You can join the study and help collect survivorship data:

Link to Monarch Larval Monitoring Project

  • It's easy to find monarch larvae when you look for leaf damage on milkweed leaves. Predators and parasites may cue in on leaf damage to find their prey. For this reason, larvae of some butterfly species change their position on the plant often, and move to different plants, as a predator avoidance strategy.
  • When frightened, larvae use a silk lifeline to escape quickly. They can drop to the ground and vanish in the vegetation in an instant. They also often curl up into a ball when touched. Why do you suppose they do this?

Monarch Fair: Real-life Examples of Student Research With Monarchs!
Students can study questions such as these by designing their own research. Monarch larvae are fun and fascinating to study. Visit the Monarch Fair online and you'll be inspired to see what students have learned!

Try This! What if Your Weight Increased 2,000-fold?
Imagine gaining 2,000 times your weight in only 9-14 days, the way monarch larvae do! Multiply your own weight by 2,000. What can you find that weighs the same amount? This writer would weigh the same as 32 female elephants!

First try to work though the problem yourself. If you have trouble, check my math as an example:
  • My weight = 125 pounds
  • 125 pounds X 2,000 = 250,000 pounds
  • 1 female elephant weighs 7,700 pounds
  • 260,000 divided by 7,700 = 32.467 elephants (But please permit me to round off to 32 elephants!)

What Would be Your Size if it Gained 2,000 Times its Weight?
Here's another way to look at this amazing growth rate. Find something that's 2,000 times lighter than you are. Convert pounds to grams as helpful starting point. (Link to Metric Conversion server.)

First try to work though the problem yourself. If you have trouble, check my math as an example:
  • My weight is 125 pounds
  • 1 pound is .4536 kilograms
  • 125 pounds is 56.7 kg
  • 1/2000 the of 56.7 kg is .028 kg
  • .028 kg is 28 grams
  • What weighs 28 grams?
  • Food servings are shown in grams, so I searched the cupboards.
  • A granola bar is 26 grams, so if a granola bar grew to 2,000 times its weight, it would be about my weight.

Noticia de la migracion de la mariposa monarca: 15 mayo de 2001
As the butterflies fly over your homes, schools and cities, we're sending the news back to the students in Mexico so they can track the migration too. Here is this week's report in Spanish, with an English translation:

Please report the FIRST MILKWEED to Emerge This Spring!

Journey North
Year End Evaluation
Please share your thoughts

The Next Monarch Migration Update Will Be Posted on May 23, 2001


Copyright 2001 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to our feedback form

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