Monarch Butterfly Migration Update: April 18,
2003
News From Along the Migration Trail But fresh-winged butterflies will soon replace their parents, and continue the migration northward. Now's a good time to print the Migration Route Prediction Chart and be ready to fill in more states as we go: Why Fewer Monarchs in April? Discussion of Challenge Question #16 Mrs. Nunnally's second grade class at Peter Woodbury School in Bedford, New Hampshire, believe fewer and fewer monarchs are seen in April because, "the monarchs coming back from Mexico are starting to die. Then more are seen in May because they are new monarchs that came from the eggs that were laid by the first monarchs migrating north from Mexico."
Exactly! And first evidence of the next generation has already appeared in Texas... New Generation Now on the Wing "We started having our first monarchs (from eggs found in the wild) eclose this weekend," reported Harlen Aschen from the Texas Gulf coast on Monday, April 14. ("Eclose" means to emerge from the chrysalis.) In addition, Janis Lentz's Classes in Weslaco, Texas, reported to Monarch Watch, "Our first adult monarch of 2003 emerged on the morning of April 8. We found the egg on native milkweed on March 16, and the monarch formed a chrysalis on March 28." Observers: Please Watch the Wings When you report your first monarch this spring, please note the condition of the wings. Are they tattered and torn--or fresh and brightly colored? Let’s see if we can document when and where the first spring generation appears.
Larva Locomotion: A Closer Look Those of us impatient to see our first monarch of spring should be glad monarchs migrate by flying, not walking! This video clip shows the process in slow motion. But before you watch:
The Next Step: Some Anatomy All insects have six legs. That includes monarch butterflies, even in the caterpillar stage. This picture shows one side of a caterpillar. If you count, you might think you're seeing 8 pairs of legs. But the leg-like structures you see, in the rear, are not actually legs. They are called "prolegs." A proleg is an appendage that looks like a leg, and acts like a leg, but is not a true leg (embryologically speaking). How are the monarch's prolegs different from its true legs?
How Do Larvae Walk? NOW, watch the video clip and describe how a monarch caterpillar walks:
(To respond to these questions, please follow the instructions below.) How Much Would You Weigh? Discussion of Challenge Question #17 We asked, "How much would you weigh 9-14 days from now if you gained 2,000 times your own weight? (With your answer, name something that weighs the same amount.)"
The larva's skin stretches and stretches during growth. Then, when additional stretching is no longer possible, the caterpillar sheds its skin (it "molts"). The different stages of growth, between each molt, are called instars. A monarch larva goes through five instars before becoming a chrysalis. Caterpillar Identification Quiz Discussion of Challenge Question #18 Last week we asked about the tiny larva that was misidentified. "How can you tell the difference between a monarch larva and a queen? What characteristic can be used to separate the two?"
"Queens have a third pair of tentacles," said Mike Quinn of Texas Parks and Wildlife, when he pointed out our error. Mrs. Swentzel's third grade class from Stanhope, NJ, observed the two different caterpillars carefully. Look at the many differences they noticed!
Milkweed Emerging Along the Migration Trail Please help monitor the spring emergence of the monarch's food plant across North America. You'll be amazed at the close connections the migration and this all-important plant. Please REPORT when your milkweed grows!
How to Respond to Today's Challenge Questions: IMPORTANT: Answer only ONE question in each e-mail message. 1. Address an e-mail message to: jn-challenge-monarch@learner.org
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