To: Journey North
From: Karen Oberhauser,
University of Minnesota
Department of Ecology, Evolution and Behavior
o all of the Journey North Students following the monarch migration:
Thanks for you good questions. As I said last year, there are many that I can't answer, because they haven't been studied. There are many things that are very difficult to learn about insects. A good exercise would be to try to come up with suggestions as to how you would learn answers to questions that I can't answer. Remember that scientists need to work within time and money constraints in answering their questions!
Many of you may be also following the Monarch Watch homepage. This is a WWW site devoted to monarchs, and has lots of good information. If you haven't already done so, I encourage you to look at this site.
Happy monarch watching! Karen
From FLORIDA:
Q. What tells the monarchs to migrate?
A. We're not sure exactly what cues the monarchs use. We do know that those that migrate emerge in a state of "reproductive diapause," which means that they won't reproduce at four to six days of age like summer monarchs will. We also know that some combination of information from daylength, temperature, and possibly the age of the plants they are eating triggers this state.
Q. Why do the females have thicker wing veins?
A. I don't know. This is a good question! It's possible that insect physiologists know the answer, but not me.
ohssci@gnv.fdt.net (OHS Science Lab)
From ALABAMA:
Q. Can butterflies travel over the ocean, and could butterflies land on water?
A. They do travel over the ocean - we know this because they are sometimes found on islands and oil rigs in the ocean. We don't know if these butterflies are blown off course, or if they "mean to" fly over the ocean. It is likely that many monarchs that start over large bodies of water die, since they probably couldn't survive after landing on water.
Q. Do butterflies in the north have a differnt chemical makeup because milkweed they eat is different from the southern milkweed?
A. Yes they do. Dr. Lincoln Brower and people working with him have used these differences to determine where adult butterflies they capture came from.
Q. Can they fly in the rain?
A. No, at least not for long.
Q. How do they know which plant is a milkweed?
A. They use a combination of visual and chemical cue to find milkweed. Once they land on a plant, they use sensory organs on their feet and heads to tell them if it is a milkweed, and probably the quality of the milkweed.
Q. What is the most abundant kind of milkweed in the U.S. and in Mexico?
This varies a lot in different areas. Where I live, common milkweed, or Asclepias syriaca is most abundant. Other species are more abudnant in other areas. For a nice description of many kinds of milkweed, you could look at the Monarch Watch homepage (http://monarch.bio.ukans.edu).
Q. How are monarchs able to fly so far and know where to go?
A. This is a good question that I wish I could answer. We don't know!!! Isn't it nice that there are still a few mysteries in the world?!
Laura McCagaren, Antoinette Pulliam, Katherine Pargeon, and Katelyn Braswell
Sixth grade students at J.F. Drake Middle School
Auburn,Alabama
Carol D Rogow <rogowcd@mail.auburn.edu>
Library Media Specialist
From ALABAMA:
Q. How is the gold formed in a chrysalis and why?
A. We don't know why. The color itself comes from cardenolides in the milkweed that larvae eat.
Q. If a bee stings a monarch pupa, will it turn into a bee ?
A. There are a few species of parasitic wasps that lay eggs in monarch larvae and pupae (this isn't really stinging them, but it looks like that's what they're doing). These eggs turn into wasp larvae that eat the monarch, then pupate and turn into new wasps.
Q. Do monarchs have scent glands, and do they use scent markings to guide their migration North?
A. They do have scent glands, but it is unlikely (but possible, I guess) that they use these to guide their migration. If they marked plants on their way south, most of the leaves they'd marked wouldn't be around the next spring! Maybe you could come up with a hypothesis for how this kind of scent marking would work.
Daniel Newton,Roland DeWitt, Randy Berrows,Zachary R. Smith
5th Grade Students
J.F. Drake Middle School
Auburn, Alabama
rogowcd@mail.auburn.edu
From ALABAMA:
Q. How far do monarchs travel in one generation?
A. It depends on the generation. The ones that emerge in the late summer and
fall in the northern US will travel all the way to their overwintering
sites in Mexico, and then about half way back in the spring. How far is
this (measure it on a map)? Other generations don't travel so far. Why?
Q. What is the function of the gold on the chrysalis?
A. see above
Wryn Vance and Shree Sarathy
6th grade
J.F. Drake Middle School
Auburn, AL
rogowcd@mail.auburn.edu
From ALABAMA:
Q. How do monarchs find their way to the north and back to Mexico?
A. see above
Q. How do their internal clocks work?
A. We don't know exactly. Can you think of a good way that they should work to allow the monarchs to do what they do?
Q. Are there laws protecting monarchs and their enviroments?
A. In Mexico, some of the overwintering sites are protected. The Canadian government is also working on protecting monarch habitat. Unfortunately, there are no specific laws in the U.S. What kinds of laws do you think we'd need to protect them in their breeding grounds here? What kind of land should be protected? It might be harder to protect them in the U.S. Why? Is there anything you can do to help?
J.F. Drake Middle School
Auburn, AL
rogowcd@mail.auburn.edu
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