Answers From the Monarch Butterfly Expert
Spring 2010

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



Dr. Karen Oberhauser

From: Virginia


Q: How old were you when you started to get interested in monarch butterflies?


A: Ten.

From: Wisconsin


Q: How many miles do individual monarchs migrate?


A: The distance varies a lot, probably on average about 1500-2000 miles. You can look at map and make some estimates yourself – try measuring the distance from northern Maine to the wintering sites in Mexico. This would be one of the longer distances.


Q: Why are they called "monarchs?"


A: Nobody really knows this for sure. It’s possible that monarchs were given this name because they are so large and majestic. But the name may have also come from King William III (from England), who was called Prince William of Orange (get it?) before he became king.


From: Texas

Q: Is there a fungus that affects the chrysalis? I have had problems losing several chrysalis. They just turn black. Also, during the process some caterpillars just hang and die.


A: There are many diseases and parasites that kill monarchs, including viral, protozoan, fungal, and bacterial infections. These often kill the caterpillars just before they pupate, or during the pupa stage. If you’re having a lot of problems with this, you might want to consider rearing them in separate containers to see if you can avoid this problem in the future.


Q: What type of bug is red and black and loves to be on the butterfly weed?


A: Milkweed bug or milkweed beetle – try looking these up on-line and seeing which it is you have. I recommend the book Milkweed, Monarchs and More for descriptions of many of the cool things you can find on milkweed plants. You can order it from the MonarchLab store.


From: Tennessee


Q: On the crysalis at the lower edge of the top region is a ring of gold dots. Of what substance are these composed? Do they have any special function?


A: Fred Urquhart first studied the gold spots on monarchs in the 1970s. He felt that the spots were involved in the distribution or formation wing scale coloration. However, the experiments that he did involved cauterizing the gold spots on the pupa, and it is possible that this process may have damaged the underlying tissue and affected the color patterns. Interestingly, all /danaine/ butterflies (monarchs and their relatives) have metallic spots on them. A group of researchers in Germany did a careful study of the properties of these spots. They are not metallic (so they aren't really gold), but the cells reflect light like metals do, giving them the appearance of being metallic. Other danaids have silver, copper, or gold spots.


Here are some hypotheses for the reasons that these butterflies have metallic-looking spots on their pupae:

a) camouflage they could reflect colors of the surroundings and break up the shape of the pupa; they might also look like dew droplets.

b) Warning coloration

c) Filtering particular wavelengths of light which might be harmful to the monarchs

d) They might not have any function, but just be the result of something else in the cuticle of the insect.

From: Wisconsin


Q: Is there a Monarch generation that doesn't migrate (either north or south) away from where it emerges? Have tagging studies during the summer months shown that at a certain latitude and date range Monarchs stay where they are for their entire butterfly life?


A: Migration is defined as directional movement, so monarchs could move quite far from where they emerge, and still not be migrating. "Conventional wisdom" is that monarchs that emerge in the northern part of their summer range (i.e. north of the southern part of Lake Michigan, or so) in June or early July don't move far, at least in a directional way. It is difficult to do tagging studies during the summer, because monarchs are not concentrated in a single area. However, I did some work on this many years ago, and caught many adult monarchs (especially males) at roughly the same location over several weeks. There is a description of the different monarch generations, and where we think they go (or don't go) at this link.

From: Pennsylvania


Q: Is any work being done on making more efficient cook stoves in Mexico? We read about families around the sanctuaries using the trees for firewood. This year we corresponded worked with a Peace Corps volunteer in Senegal who helped the people there plant trees and make efficient cooking stoves.


A: Yes, there is a wonderful organization named Alternare in Mexico that is doing exactly what you suggest. The Monarch Butterfly Fund ( supports Alternare with annual donations to support this work, if your class would like to make a donation to help with their work.

From: Oklahoma


Q: My last years pupae turned black as if they'd been charcoaled..most died....almost no survivors last year.. some were tachinid caused.. this was new to me...we had 9 weeks of rain prior to their arrival.. could rain have caused a virus which caused this problem?


A: There are many diseases and parasites that kill monarchs. It’s possible that your problems were linked to rain, but also that some viral, protozoan, fungal, or bacterial infection got into your monarchs and spread from one to the other. If you aren’t already doing this, you might want to consider rearing them in separate containers to see if you can avoid this problem in the future.

From: Massachusetts

Q. How are the monarchs doing after the big floods and landslides in Western Mexico?


A: The Journey North and Monarch Watch websites have lots of good information on the effects of the floods near the monarch wintering sites in February, as does our 2010 Monarch Larva Monitoring Project newsletter. In short, the heavy rains probably killed many monarchs. It’s going to be very important to monitor monarch numbers this summer to see if there are lasting effects.


From: Illinois


Q: I understand that monarchs migrate to Mexico - from both sides of the Mississippi River. From what I know they fly to Mexico and then return. I am confused because I understand that the life span of the Monarch is very short. How can a monarch migrate when its lifespan is so short?


A: The generation that migrates lives up to 7-8 months. Read about the different generations at this link.


From: Ontario


Q: I have been asked to officiate at someone’s marriage ceremony and I would like to obtain several butterflies to be released at the ceremony which will be a garden wedding. How would I go about this?


A: I recommend against using living organisms as ceremonial trinkets, unless the act of releasing and raising them has special meaning or educational value to the individuals involved. Purchasing the live butterflies doesn’t provide much educational value, nor does it really benefit the butterflies.


From: Texas


  Q: Is it true that in recent years as many as 80% of monarchs wintering in Mexico died do to exposure to freezing weather and mountain deforestation?


A: In 2002 and 2004, winter storms killed up to 60-80% of the monarchs in some of the colonies.


Q: Is the monarch migration threatened as a phenomenon?


A: Yes, monarch migration is officially listed as a threatened phenomenon by the IUCN.


Q: Why are the Mexican government and the international NGO's unable to protect the wintering habitat of Monarchs?


A: This is a very complicated problem, and one that is not unique to the monarch wintering sites. All over the world, biologically important ecosystems are being lost at an alarming rate to human uses. A lot of the lumber from these sites probably ends up in the US, in things like avocado packing crates. Recent studies have shown that most of the illegal logging in these sites is done by logging companies, not by the local people, and that existing laws are not being enforced effectively. If this is something that really interests you, I recommend this paper, which you can find online:


Honey Roses, J. 2009. Disentangling the proximate factors of deforestion: the case of the Monarch Butterfly Biosphere Reserve in Mexico. Land Degrad. Develop. 20: 22–32 (2009)

From: Iowa


What is OE?

OE is a disease that affects monarch butterflies. OE is a parasite. Its scientific name is "Ophryocystis elektroscirrha" so it is called "OE" for short. For more information about OE see the Monarch Health website.

Q: I 'foster' Monarchs. I harvest eggs, raise the caterpillars, then release the Monarchs. (One year I released over 400!) What is the best solution to 'wash' the eggs & milkweed leaves to prevent OE/parasites. I've heard several different things, from different sources. I live in a city in Iowa.


A: I actually don’t think that it’s necessary to wash the eggs and leaves. What is important is to be very careful to keep all of your rearing equipment as clean (sterile) as possible, and not to handle eggs or larvae after you’ve handled adults. We use 20% bleach to sterilize everything. You can read more on the raising monarchs section here.


Q: I've noticed that the Monarchs lay eggs on one other plant in my yard, other than milkweed. It must be in the milkweed family, as it has pods in the fall. I brought it to my local garden store, they thought it was climbing morningstar. Is this an adaptation? A previously undocumented happening? Or are some of the Monarchs just not too bright? These eggs DO hatch, and the caterpillars do eat those leaves! Any ideas?(I live in a city in Iowa)


A: I’ve never heard of climbing morningstar. Could it be /Cynanchum laeve/? This is in the milkweed family, and fits your description.

From: Ontario


Q: Just a comment in response to this question and your answer: Q. Do monarchs live in other parts of the world besides Mexico and the USA? Don't forget Canada! We have tons of monarchs up here!


A: Yes, you do! Well, maybe not tons, but certainly lots.

From: Florida


Q: I live in Port St Lucie, FL, have about 45 or more Milkweed plants in my yard and usually in winter I always have Monarchs. My plants (and house!) are swarming with cats and eaten up by late March. Not this year. Has the winter population moved further south? I harvested and raised 3 cats in Jan when I realized the cold was affecting them and there were no adults. Their cocoons hatched inside after 25 days-not 10- into healthy adults. I hated to release them in the weather. Has the weather killed our Florida Monarchs? Since mid Jan I saw one lone male in mid- Feb.How has the weather affected them?How and will the population recover?


A: It would be really interesting to report your findings on the Monarch Larva Monitoring Project website. Until people report what they’re seeing in Florida, we really won’t know what the patterns are. But cold weather (below about -5F) does kill monarchs, at any stage, and definitely slows down their development.

From: Florida


Q: Does the golden yellow New Zealand invasive wasp kill or lay eggs in emerging caterpillers?


A: Many wasps are predators while they are adults; I’m not sure just what species you’re referring to here, so I can’t be sure. Predatory wasps often eat caterpillars. There are also many parasitoid wasps, which do lay eggs on larvae or pupae, and then the developing wasp larvae consume the caterpillars from within.


Q: Is the NZ invasive wasp a real problem or just another natural enemy for the monarch?


A: If it’s invasive, it’s not a natural enemy.


Q: Is there anything that can be done about the NZ wasp?


A: I don’t know.


From: Texas

Q: Can Monarchs change their migration route or destination because of the weather?


A: They can change their migration route, but their destination is fairly constant from year to year.


Q: What makes Monarchs orange and black in color?


A: They have pigments on their scales, similar to the pigments in your hair and skin.


Q: Why isn't the milkweed plant poisonous to the Monarch larva and butterfly?


A: They have evolved to be able to withstand these toxins. Chemicals in their bodies allow them to tolerate toxins that would harm other species.


From: Arkansas

Q: We were able to experience a migration of Monarchs 3 years ago. We were building our house when they showed up and flew over our hill. They were like snowflakes. We haven't seen them since.


Q: How do we find their local migratory path again?


A: The path varies from year to year, so I would just keep looking. Perhaps you could try reporting what you saw to your local newspaper, and encouraging other people to report what they see. You could also log onto the Journey North website to see where people are reporting monarch roosts during the fall migration.


From: Texas


Q: Did the bad weather in Mexico hurt the Monarch Migration in Mexico?


A: The Journey North and Monarch Watch websites have lots of good information on the effects of the floods near the monarch wintering sites in February, as does our 2010 Monarch Larva Monitoring Project newsletter.


In short, the heavy rains probably killed many monarchs. It’s going to be very important to monitor monarch numbers this summer to see if there are lasting effects.


Q: Our milkweed froze in our school garden here in Freeport, TX. We are planting more today. Will there be enough milkweed to support the Spring Monarch Migration?


A: I hope so!

From: Georgia


Q. Do monarchs have a nose and if so can they distinguish between smells? Ian Brinson and Carey Tyler


A: They can distinguish smells, but not through a nose. Monarchs have sensory organs all over their bodies, but concentrated on their antennae and feet, which detect molecules in the air. When you smell things, that’s what you’re doing too.


Q: Are monarchs affected by earthquakes? Madison Croft


A: Certainly if the earthquake destroyed their habitat, they would be affected. We don’t know if they can sense earthquakes and respond to them.


Q: Do monarchs have leaders and if so, how are they identified?


A: Probably not.


Q: Do colored pots attract butterflies?


A: I don’t know.


From: Virginia


Q: About a year ago last Oct. I observed a hornet attacking a monarch repeatedly when the monarch was trying to feed on some aster blooms. When I knocked the hornet off the monarch (with a long twig) the hornet went to a second monarch and attacked it until I again knocked it away. Do hornets normally attack monarchs like this? This happened when there weren't many other flowers remaining in bloom--but lots of asters in three different clumps. The hornet was probably one that had survived being burnt out of its home in a tree that was felled and burned by a neighbor a couple of days earlier.


A: Hornets definitely prey on monarchs, but I’m more familiar with them attacking the larvae. There are reports of wasps eating monarchs during the winter in California, but I haven’t observed this during the summer breeding season.


From: Michigan


Q: We received monarch larva through the Butterflies in Space program. They came with their food. We place them in the same little containers they had on the ISS. However we discovered some things and wondered what might have happened. Out of six larvae one pupated and stayed green the entire time. When he emerged he made it halfway out and never came further. He died that way. The second one pupated and fell to the floor of the container two days later. He landed in food, stayed green and tried to emerge with the same results as the first. The third pupated and turned black two days into the chrysalid. the fourth made the little "j" and then stretched out and died. The last two died as caterpillars. What happened? Any ideas?


A: This sounds like your larvae were just weak for some reason. It’s hard to tell why, but the failure to pupate or emerge completely is fairly common. I would recommend reporting this to Monarch Watch to see if they’ve had other reports of larvae from this program having similar problems.

From California



Q: My students were wondering about what endangers the monarch. We often see monarchs lying on the highways. Are they harmed by things they are eating and what are their predators?


A. If they are lying on the highways, I would guess that they were killed by cars.