Answers From the Monarch Butterfly Expert
Spring 2001

Courtesy of Dr. Karen Oberhauser
(Back to Monarch Butterfly FAQ)

Special thanks to Dr. Karen Oberhauser for providing her time and expertise in responding to your questions.

  • Visit Karen's "Monarchs in the Classroom" education program Website called "MonarchLab"


Q. What is the correct answer to this question: "What purpose do you think is served by the behavior known as the "cloud effect'. That is, why do you think the butterflies suddenly fly into the air the moment the sun goes behind a cloud?". We have been unable to find any further information about the cloud effect - please forward more information.

A. Bill Calvert is the expert on this. You can read his description and possible explanation on the Journey North Web site:

Ferguson Middle School

Q. What happens to all of the butterflies who do not mate? Do they die sooner or live longer?

A. I've done some experiments studying just this question. I thought that males that didn't mate might live longer, since they weren't transferring materials to females in spermatophores. However, there were no differences in two experimental groups: males that were kept with females and allowed to mate naturally, and males that were kept in a cage without females. I have also seen no difference in females. The only monarchs who don't mate in the wild either die before they have a chance to mate, or never are successful in finding a mate. We don't think that any monarchs are in reproductive diapause their entire lives, unless they die before the end of the winter.

Greenwood Elementary

Q. I have received very disturbing emails concerning the mass extermination of monarch butterflies in Mexico by logging companies this winter. (I can forward the e-mails to you if you'd like to see the source.) Is there any truth to this? We are told that millions of butterflies have been killed. M.E. McCabe

A. I've been following this closely too. While it is possible that we will never know all of the details of what happened, the opinion of monarch biologists is that these butterflies probably died of natural causes, the most likely of which is that they were killed by a snowstorm. The greasy appearance that was mentioned in the articles was probably the result of fat (lipids) permeating the exoskeleton of the monarchs. Many of us think that the butterflies are more likely to die after a snowstorm if the forest has been degraded, and thus does not offer adequate protection. There is really no good reason that the loggers would kill the butterflies.

They need to obtain permits to log the forest, and the presence or absence of butterflies will not affect the likelihood of their getting a permit. In addition, chemical analyses of some of the dead butterflies have shown no evidence of pesticide residues.

Crestwood Elementary

Q. My husband just bought me a scarlet milkweed plant in Florida and brought it home to me in Richmond. I noticed it had 4 monarch eggs on it and took the plant to school today and 1 caterpillar hatched. We've raised monarchs in the Fall for migration but now I'm worried the butterflies will not have food. They should be (if the process is successful) emerging around the middle of April or before and I don't think we will have enough flowers at that time - how can I feed them? Will these live about 2 weeks?

A. Will you have enough milkweed to feed the four larvae? There will probably be some flowers in Virginia in April. However, I have other concerns about moving monarchs from one place to another, especially from Florida to another part of the country. Most of the monarchs in Florida are infected with a protozoan parasite called Ophryocystis elektroscirrha. This parasite is transmitted from mothers to offspring, or from males to females during mating. If these monarchs are infected, they will spread spores on all of your cages and other materials, and larvae that you raise next fall could be contaminated; if they're released into the wild, they could infect other monarchs.

PLEASE read about this disease:

R.L. Norton Elementary

Q. Dear Dr. Oberhauser, Nice to hear from you!! My class is busy trying to grow milkweed and attract those Monarchs to Georgia. They are so excited! I received an Outdoor Classroom grant to purchase plants and equipment. I am using items from Bioquip. What would you suggest for a good observation cage for rearing and observing butterflies? Take care. I sure wish I had some larva to show my class and rear.
Sincerely, You fellow Wisconsinite, Anne Marie Glawe

A. Anne, great to hear from you again! We're hoping to work more with all of the great monarch teachers in GA! I really like the 2x2x2 foot cages that Bioquip sells. Or, you could make your own cage (check out the directions in our curriculum guide). We make cages in our lab from plywood and screen that work pretty well, and the directions for these are in our guide. You just need to be a little handy with a staple gun, sewing machine, and screw driver!

Q. We are raising milkweed to place in our school garden in Snellville, Georgia. This is 20 miles northeast of Atlanta. When could we expect monarchs to be passing through the garden?

A. Keep watching the Journey North map for an up to the week report on when the monarchs will get to your garden!

Natural Outings

Q. Hi, I was part of a group of Canadians who visited the El Rosario sanctuary last week (March 4). It was fantastic. Later in the week, we read Michoacan newspapers that said there might have been a poisoning of all Monarchs in another sanctuary (Las Palomas), but the evidence was inconclusive and some said they simply froze to death. I suspect the newspapers were sensationalizing the event somewhat. They also mentioned testing in labs which would provide further evidence if poisoning was to blame. Has a definitive answer to why this mass mortality event occurred been formulated yet?
Thank you, Richard

A. See my answer to the teacher from Crestwood Elementary School above. I'm glad that you got to visit El Rosario!

Public School 56 Queens - The Harry Eichler School

Q. Where do butterflies migrate and why?

A. You can read all about monarch migration on several Web sites, including a new section on our Monarch Lab site.

Also, follow their spring migration on Journey North. A simple answer to why they migrate is that they can't survive in freezing temperature, so can't stay in places like New York and Minnesota in the winter.

Highview Elementary School

Q. Where is the best place to find a Monarch Butterfly in the summer?

A. Anywhere that there are milkweed and flowers for nectar. I find it easier to find the larvae than the adults; just look at lots of milkweed plants. If youăd like to join a whole team of people all over the country who are trying to learn more about where monarchs live in the summer, you could participate in the:

Q. How does a Monarch Butterfly know how to fly right away when it hatches out of it's cocoon?

A. Instinct. Unlike humans, insects don't have to learn much. They are genetically programmed to do things like fly, find food, and migrate (in the case of monarchs). In some ways, this sounds like a great thing. However, there isn't as much flexibility in behavior for organisms that depend on instinct. We need to learn how to talk, walk, read, etc, but think of the flexibility we have in determining what we do with our life. Insects don't have that.

Q. How can you stop the Monarch Butterflies from shivering so much when they are over-wintering?

A. They need to shiver to warm up their muscles enough to move.

North Elementary

Q. On February 21 Eligio Garcia noticed a change in the appearance of the wintering monarchs. He said this change indicated that the monarchs were preparing to produce the next generation. What changed about the appearance of the monarch that Eligio saw? Please describe this change in detail.

A. I didn't read Eligio's description of what was happening, but I've been in the monarch colonies at that time of the year, and what I notice is a big increase in the amount of mating behavior, and overall activity. If he said that they were preparing to produce the next generation, he probably meant mating behavior!

Q. My encyclopedia states that monarchs feed on milkweed and it also states that milkweed blooms between June and August. Why then are people already reporting sighting of monarchs in Fla., Texas, and Georgia if the milkweed has not bloomed yet?

A. Monarch larvae feed on the milkweed leaves, not the flowers, so the plant doesn't need to be blooming to be useful to them. The adults feed on nectar from many species of flowers. I've seen many books that say that monarchs require the leaves and the flowers of milkweed to survive, but that's incorrect. They could get by without the flowers, as long as flowers of other species were blooming.

Glenwood Elementary

Q. Do Monarch Butterfly's live only in North America? If so, Why?

A. Monarchs also live in Australia, South America, Hawaii, and several other Pacific Islands. Most scientists think that they originated in the New World tropics (North and South American) and have spread to other places in the last few centuries. This spread was probably enabled by humans, who planted milkweed in new areas, and then may have moved the butterflies on purpose or by accident.

Q. Would Monarch Butterfly's survive when there is snow on the ground?

A. They can survive short periods of freezing temperatures, but not long periods. So a snowstorm wouldn't necessarily kill them. It's worse for them if they get very wet, and then freeze.

Grisworld Middle School

Q. We understand that the Monarch stops reproduction while in Mexico. How does this happen?

A. The monarchs that will migrate to Mexico do not mature completely before they migrate. Even though they look just like normal adults, they are not sexually mature. They are sort of like a juvenile, or pre-puberty, person. This happens when they are exposed to shortening days and cooler nights during the time that they are larvae and pupae.

Q. How long does it take to shut down the reproductive cycle?

A. It happens sometime while they are developing as larvae and pupae. We don't know exactly when it happens, or how long it takes.

Q. What starts up reproduction again as it migrates in the spring?

A. When the butterflies are exposed to lengthening days, and possibly warmer temperatures, their reproductive organs begin to mature.

Charleston Elementary

Q. One of my first graders wants to know what color nectar is? Is it always the same color for each flower or does it change colors?

A. In my experience, nectar is usually clear. I've never seen any that was the color of the flower, but I haven't looked at nectar from every flower species. This would be a fun thing to test. You could get a very fine capillary tube, like the kind that they use to draw blood after they prick your finger at the doctor's office, and put it into a flower. You will then be able to see what color the nectar is.

Tell your student that this is a GREAT question!!

Watkins Elementary School

Q. How long does it take a monarch to fly from Washington, DC to Angangueo, Mexico?

A. This would depend on temperature and wind conditions. On average, it probably takes about two months, total.

Q. How do monarchs know where to go?

A. We don't know for sure. We do know that they don't learn where to go, but instead are genetically programmed to go to the right place at the right time. We also know that they use the sun as a cue to tell them which way is south. There is some information on this on the Monarch Lab Web site

Q. How do monarch butterflies excrete?

A. The purpose of excretion is to keep a constant level of salts and water in the haemolymph, or blood of the butterfly, and to get rid of toxic compounds that are produced during metabolism. Adult monarchs do this using a system of tubes called Malpighian tubules, which are found throughout the body. These tubules pick up materials from the haemolymph, and then carry them to the rectum of the butterfly. All of the materials that the butterfly doesn't need, or would be harmful to it, are then concentrated in a liquid form

Dr. Karen Oberhauser
University of Minnesota
Department of Ecology
1987 Upper Buford Circle
St. Paul MN 55108
612 624-8706 fax: 612 624-6777