Today's News Report Your Sightings How to Use Journey North Search Journey North

Ask the Expert

Answers From the Monarch Butterfly Expert

Karen Oberhauser
University of Minnesota
Department of Ecology,
Evolution and Behavior

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

"Monarchs in the Classroom", Karen's education program, will launch a new Website later this spring called, "MonarchLab". Save this address so you can visit when it opens:


Museum Magnet School

Q. Do monarchs live in other parts of the world besides Mexico and the USA? Are there different types of monarchs? From Erica

A. Yes, monarchs are found in many places throughout the world, but they probably originated in the Americas, and were spread either with the help of humans or on their own to other places. They are found in Australia and New Zealand, and many islands east of these countries (most islands between Australia and Tahiti have monarchs). They are also found in Hawaii, most islands in the Caribbean, and even sometimes in western Europe.

There are different subspecies of monarchs. Most of those found in South America are a different subspecies than the ones you see in Minnesota. In islands in the Caribbean, both subspecies are sometimes found.

Q. How are the Mexican farmers putting up with the monarch sanctuaries? From Nick

A. This is a hard question. Different farmers feel differently about the sanctuaries, just like different kids in your class may feel differently about having a governor who used to be a pro-wrestler! On the whole, I think that the farmers feel a very strong connection to the land. They understand that the preservation of forest land is vital to their own continued presence in the area. Unfortunately, sometimes their very urgent immediate needs, like finding enough for their families to eat, are at odds with long-term preservation of the forest. However, I think that many of the farmers think that long-term preservation of the sanctuaries will benefit them as well as the butterflies.

If you would like information on how you could help with some of the work we're doing to help Mexican farmers "put up with the monarch sanctuaries", check out the website for the Monarch Butterfly Sanctuary Foundation .

Q. I know that the monarchs spend the winter in the mountains of Mexico. But why don't they live in the Rocky Mountains in the summer? From Jack

A. Some do live in parts of the Rocky Mountains, but at very high altitudes, there is no milkweed. It is too cold for milkweed to grow, so monarchs couldn't reproduce there. The monarchs need warm temperatures themselves in the summer - when it's cold it takes them so long to develop from egg to adult that they wouldn't have enough time to get through even one full generation.


Q. I saw ants crawling out of a tiny hole in the pupa. Did the ants dig the hole? or did another preditor poke it and withdrew fluids and the ants were just finishing the job? It happened all summer. I gathered the pupa so no more could be destroyed. But something did make a hole in some of these too. What could it be?

A. This could be many things. Ants will eat a dead pupa, but if you saw a hole in it, it is possible that the monarch had been parasitized by a wasp, who had already crawled out. Another predator, like a mouse or a predatory wasp, might also have attacked the pupa from the outside and the ants were just finishing the job. Or, you may have seen tiny parasitoid wasps that had developed inside the pupa that just looked like ants. Are you positive they were really ants?

North Albany Elementary

Q. Do Monarchs breath in their chrysalis, and if they do, how do they? If they don't, why don't they need air?

A. The pupa "breathes" just like the larva and adult, through tiny holes in the side of the abdomen and throax called spiracles. The reason that I put quotes around the word breathes is because this is very different than the kind of breathing you do. The air goes into these holes and through a whole series of tubes in the body called trachea. The trachea carry oxygen throughout the monarch's body. They don't have lungs.

Q. How come only male monarchs have a big black dot on their wings?

A. These dots are made of specialized scales which produce a chemical during courtship. Even though this chemical does not appear to be important in monarch courtship, the males still have the spots. The spots are much larger on close relatives of monarchs.

St. Patrick School

Q. Last year, we did not see any monarchs up here. There are milkweed plants here. When I went to Bancroft in the summer, there were monarchs everywhere. How come they are not here? How can we encourage them to return to here? From Mrs. Livingston and her Grade 4 class

A. We don't know what causes the big changes in where monarchs can be found each summer, or how many there are. We see the same things in Minnesota. Some years there are a lot in certain places, some years we don't see any. We are tyring to study this very thing with a large monitoring project all over the US and southern Canada. The best thing you can do is just have a spot that is "monarch friendly." Keep lots of milkweed, flowers, and open space available, and hopefully they'll come back.

From: OHIO

Q. I have been gathering larva in the fall the past 25 years for classes. It seems that I have noted a very distinct drop in larva found in August to early September (in northeastern Ohio). Is this a pattern for this area? Are there reasons why we may be seeing fewer Monarchs?

A. See my answer to the above question. We really need consistent, long-term data to answer this question. Insect populations are notorious for large fluctuations, and we don't know if the low numbers we've been seeing lately are just a "natural dip" in population density, or if they mean that humans have changed or usurped monarch habitat, or caused other environmental changes that have harmed the monarchs. If you (or anyone else) would like to help in our monitoring project, you can. This involves weekly monitoring of a site that has milkweed, and takes about 2-3 hours per week. For more information, you could e-mail Michelle Prysby, who is directing this project (

Griswold Middle School

Q. Are there monarchs living on other continents?

A. Yes. I'll copy the answer I gave above. Monarchs are found in many places throughout the world, but they probably originated in the Americas, and were spread either with the help of humans or on their own to other places. They are found in Australia and New Zealand, and many islands east of these countries (most islands between Australia and Tahiti have monarchs). They are also found in Hawaii, most islands in the Caribbean, and even sometimes in western Europe.

Q. Can you tell the differance between a male and female monarch when they are in the larval state?

A. Only if you dissect them and look for the male's testes. In some butterfly species you can see these testes from the outside, but not monarchs.

Q. Do the males look for food more than the females?

A. I don't think so, but I've never studied this nor read about anyone else's study of this question. How could YOU answer it?

Locust Valley Intermediate School

Q. If the female mates and is ready to lay her eggs and can't locate milkweed plants ,what does she do? Does she lay them on any plant she finds? If that is so, what becomes of the caterpillars?

A. Females will wait a long time to find milkweed. Sometimes in our cages we keep mated females without milkweed, and VERY rarely, we will find a few eggs on other plants or the sponges we use to feed the females. The caterpillars then die. That's a bad situation for females to be in, and their reproductive cycle is closely coordinated with their environment so that it doesn't happen too often. We have done studies here at the University of Minnesota that have shown that having milkweed around actually speeds up egg development in females that were overwintering in Mexico.

Q. When the monarchs go to Mexico how do they know where they are going?

A. This is a question that scientists are still working to answer. People working at the University of Kansas with Chip Taylor have shown that they use the sun, and also probably the earth's magnetic field to know which way is south during the fall migration. But we don't know how they find the specific spots in Mexico. Personally, I'm not sure that we'll ever be able to answer this one - which I think is kind of nice. I like mysteries!

Q. Did you ever tag and track a specific group or colony of monarch butterlies to see where they are taking their journey to? If so, what were the results of your tagging?

A. No, I haven't done this. People working in the California colonies have, though. Just recently, Paul Cherubini from CA, made the following statement on the Monarch Watch listserve. "Monarchs tagged in the Santa Barbara area overwintering colonies have been recovered in all possible directions (e.g. in extreme southern California, Arizona, Nevada and throughout northern California)."


Q.With the recent logging practices in Mexico what impact do you feel will result in future monarch population numbers ?

A. I think that unless the rate of logging decreases, future monarch population numbers will be much lower. It is VERY important that the overwintering sites in Mexico are preserved. Of course, it is also VERY important that suitable breeding habitat and migratory routes in the US and Canada are preserved. We all need to work together to ensure that your children will still be able to study monarchs in their classrooms twenty or thirty years from now.

Karen Oberhauser
Department of Ecology, Evolution and Behavior University of Minnesota
1987 Upper Buford Circle
St. Paul MN 55108

Copyright 1999 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to our feedback form

Today's News Report Your Sightings How to Use Journey North Search Journey North