Clockwork Orange: Like clockwork, each fall millions of fragile monarch butterflies from northeastern America journey 4000 km to a small area of central Mexico, to winter amidst the sacred fir groves. In the spring, the butterflies mate and begin their fluttering journey back north.While individual butterflies complete the southward journey, a succession of short lived generations make their way back north.

Treasure trove of Navigation:This marathon is unparalleled in the insect world and approaches the sophistication of vertebrate animals, like birds. Yet, the brain of a monarch butterfly is no larger than a pinhead! They cannot learn this behavior because migrant butterflies are separated by at least two non-migrant generations. So how do they do it?

Built in GPS: Butterflies use the sun as compass. As the sun moves east to west over the course of the day, they use an internal circadian clock to make adjustments. The clock resides in their antennae and in the brain. (If the antennae are dissected out, they continue to show cyclical changes that can be entrained to light.) Special cryptochrome proteins control these cycles. They also use magnetic fields for navigation: magnetite (iron oxide particles) that may sense magnetic fields have been found in butterflies, or they may use “light-dependent magnetoreception”.

Genome for a King: Recently, the genome of the monarch butterfly was completely sequenced, revealing 16,866 genes spread out over 273 megabases of DNA. Genetic regulation pauses the reproduction of migrating monarchs, greatly increases life span, abdominal fat stores, cold tolerance and wanderlust! Despite being the same species, interim generations do not make the long trip. A subset of regulatory molecules (microRNAs), buried in the genetic map, are expressed differently in migratory monarchs relative to the nonimmigrant generations.

Milkweed Specialization: Larvae feed exclusively on poisonous milkweed (Asclepias) which contain cardioactive glycosides (used to treat heart failure). The chemicals inhibit the sodium pump found in all animal cell membranes but monarch butterflies are resistant because they carry two mutations in the drug binding site of the pump. This makes them highly unpalatable to predators and lets them flaunt their gaudy colors with impunity!

WATCH: The Pacific Grove habitat of non-native Eucalyptus attracts millions of butterflies as explained in the video in this link via Ron K Jeffries : http://science.kqed.org/quest/video/science-on-the-spot-monarch-meetup/

LISTEN: “Before I sink into the big sleep, I want to hear, I want to hear, the scream of the butterfly” (from When The Music’s Over The Doors, 1967). The Doors – When The Music’s Over (LIVE IN EUROPE 1968) This was the opening quote of a free review on Navigational mechanisms of migrating monarch butterflies found here: www.ncbi.nlm.nih.gov/pubmed/20627420. Cool science and music!

For ScienceSunday #sciencesunday

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  1. amit sekhar says:

    hiiiiiii……nice1…….miss rajni

  2. Johan Horak says:

    Rajini Rao Amazing info to read while I Listen to When The Music’s Over. Have not listen to this song for many years.

  3. Lovely Photo ! & thanks a LOT 4 the information !!! I had some info about Monarch butterfly but these r AWESOME !! Thank u !!!

  4. Rajini Rao says:

    How could I resist an opportunity to sneak in the awesome Jim Morrison, Johan Horak ? 😉 Monarch butterflies are awesome too…

  5. Rajini Rao says:

    Peter Lindelauf , there are western migrations too; in fact the video in the link describes them. Ron K Jeffries knows a lot more about this. BTW, by NE America, I mean the continent, so more accurately that would include SE Canada. Let me find some maps for you. EDIT: Maps in the link I provided on Review of Navigational Mechanisms.

  6. Rajini Rao says:

    Aww, what a lovely thought Kimberly Brosnan .

  7. Very…Very nice….like Thank’s…

  8. Rajini Rao says:

    I wonder if some humans are compelled by their unique genetic makeup to be bitten by wanderlust while others are content to be home? These are powerful chemically driven urges. Also, only the migrant generations cluster in enormous crowds on trees..their genes unexpectedly revealed pheromones that are thought to drive migration induced social behavior.

  9. Where I used to live in Texas, the monarchs came through every year; it is quite an amazing spectacle.

  10. Thanks for a great article, Rajini Rao Monarchs are indeed wonderful creatures. There’s still a lot we do not know. The recent genome sequencing is so informative. For those reading this piece, plnting milkweed is an affirmative action you can take to help monarchs. Milkweed availability has been much reduced by urbanization and spraying of weeds along highways. I have a lot of seeds, just ask. 😉

  11. CHRISY jothi says:

    How they measured the distance travelled by these butterflies? It is unbelievable

  12. Rajini Rao says:

    Peter Lindelauf , that sounds right…the west coast Monarchs are largely seen along the Monteray Bay area south of San Francisco. I was lucky enough to be there during a conference, coincidentally, on sodium pumps (which are the target of milkweed cardiac glycosides).

  13. Rajini Rao says:

    I’m not sure if researchers have gotten around to implanting microchips to monitor butterfly migration, but the technology is definitely available. I’ve merely skimmed the surface of the research, but I had the impression of extraordinarily sophisticated stuff published in top ranking science journals.

  14. Peter Lindelauf West of the Rocky Mountains, Monarchs overwinter at about 20 sites along the California coast. I volunteer as a docent at the Pismo Sate Beach Monarch Grove, one of a handful of large sites. Anther large overwintering site is near Santa Barbara — Ellwood in Grove in Goleta. That site had about 60,000 Monarchs this winter.

    There is some indication (no hard science yet) that a small population of Monarchs may stay in California year round. There is a similar situation in the southeast, where it is documented that a non-migratory monarch population has evolved.

    Since milkweed is the only host plant used by monarchs to lay eggs, it follows that is milkweed is available year round, there is no compelling reasons for migration.

    Semi-unrelated factoid: there is a population of Monarchs in Hawaii. Somehow a mutation has occurred where some monarchs there have black and white coloration.

    I am NOT an expert, so take all that I say with several grains of salt.

  15. Oh God you cannot miss them.They are beautiful

  16. Rajini Rao says:

    For our international readers, these butterflies are also found in New Zealand and Australia (where they are called Wanderers, how lovely!), in Canary Isles/Azores, in India/Sri Lanka, occasionally in West Europe and UK (where they are named Milkweed Butterfly).

  17. Farzad Turk says:

    Pacific Grove California is also home to Monarch Butterflies but unfurtunitly they are showing up less and less, don’t let what is happening to Bees and thier Colonies happen to Butterflies as well. stop spraying chemical on open fields or we are all next to go. great picture Rajini

  18. During migration, monarchs only fly during the day. Air temp needs to be 55F or higher. They have been observed flying over the Great Lakes. One observer witnessed monarchs landing on an ore-carrying barge to spend the night. In the Gulph, there are credibel reports of monarchs landing on oli rigs to spend the night. There is a shortcut some of them take to Mexico that takes them over a not very wide expanse of the gulf of Mexico, but that seems to be th exception rather than the rule.

  19. Rajini Rao Monarchs cluster (we think) for protection from wind and rain. If you find research on social behavior taht will be of interest. Their mating habits are interesting. The male catches a female in flight, takes her down to the ground. She sometimes rejects him, and sometimes he has mistaken another male for a female.

    Once the male and female “hook up” (in the literal sense) he flys upward in circles to reach as in a tree as possible. Think of what an effort this is, as he carries her weight in addition to his own. (One assumes that weaker makes can not do this and thus their genes do to carry forward).

    Once the pair reaches their honeymoon spot, they remain together for as much as 24 hours.

    Females are not monagomous. They breed as many times as there are opportunites. The genetic materia;l from the last male to breed with her “wins.” Other sperm is absorbed as a source of nutrition.

    Eggs are NOT fertilized until they are secreted, one at a time, by the female after she finds milkweed. One female will have between 200 and 500 eggs. In captivity, a lab specimen female was examined that had over 1,000 eggs.

  20. Chad Haney says:

    The Gibson G-101 combo organ was used by Ray Manzarek of The Doors. The Gibson G-101 was initially called the Kalamzao K-101. Orville Gibson started in 1894 in my hometown, Kalamzoo, MI. From the Wiki: The “Glide” effect pitched the notes flat by a half-step when actuated by a side-lever on the expression pedal. This effect was used by organist Ray Manzarek of The Doors on the recording of “Not to Touch the Earth” http://youtu.be/d_-HqcNum7M

    OK, you knew it had to come to Pink Floyd. Richard Wright used a similar organ, the Farfisa Compact Duo on The Pipers at the Gates of Dawn. He switched to a Hammond organ for The Dark Side of the Moon.

  21. Chad Haney says:

    Ron K Jeffries, I’m not a big fan of milkweed but you’ve given me a reason not to pull it out when I’m weeding.

  22. Rajini Rao says:

    Woah!! To Ron K Jeffries and Chad Haney for some awesome (albeit different) information. Thanks 🙂 Feisal Kamil , hmm..the gender difference with males being more “peacock colored” may be restricted to vertebrates..let me look into it.

  23. Chad Haney says:

    I’m surprised none of the mathematicians or physicists have mentioned the Butterfly Effect yet. http://en.wikipedia.org/wiki/Butterfly_effect Maybe because there isn’t a Monarch Butterfly Effect.

  24. aqui en mi pais somos afortunados en darles posada a las monarca en invierno saludos

  25. Rajini Rao says:

    Oh yes, Chaos Theory..a funny cartoon with a literal interpretation of this went by my stream some days ago :). Feisal Kamil , believe it or not, there was a research paper on gender differences in wing color in monarchs 😛

    Apparently, the differences are modest, but the males do have a deeper hue: “I found that males and females differ statistically in wing hue, with males tending to have a deeper orange color than females. This species was already known for another sexually dimorphic trait, in that females have a greater degree of black pigmentation [8], see Figure 4, but it would seem that the sexes differ in other features as well.” Source: http://www.hindawi.com/journals/psyche/2009/705780/

  26. Great article, thanks for posting Rajini. You may be interested to know that we have Monarchs in New Zealand – and they are believed to have flown/blown here (from North America) about 160 years ago. They would have no doubt been on their migration and been carried here by a rogue wind. Now THAT is a long flight!

  27. Rajini Rao says:

    You’re welcome, Jacqui Knight . I love your avatar!! From what I read, Monarch’s in NZ and Australia are called Wanderers.

  28. Hi Rajini – Only in some parts of Australia are they called Wanderers. We (NZ) call them Monarchs. Interestingly enough early in each year, when there are cyclones headed our way from Australia, vagrant species of butterflies are carried here from Australia. One such butterfly is the Lesser Wanderer, Danaus petilia (was D. chrysippus petilia), a native of Africa, Asia, Australia. A couple of months back a female, egglaying, landed in a friend’s garden so we hope that perhaps we can encourage it to overwinter here!

  29. Bill Brown says:

    WOW very nice post indeed!

  30. Rajini Rao says:

    I googled it Feisal Kamil . What an unusual combination of electric green and black. The Wiki entry shows the browner female next to the male. By extrapolation to humans, a sound thesis statement would be that the male of the species is also showier than the female (ignoring clothes/makeup which are merely external modifications). Now to collect evidence…. 😉

  31. Chad Haney says:

    Feisal Kamil there are exceptions to most rules. http://goo.gl/PsCTZ

  32. Rajini Rao says:

    That’s only because men are arrogant enough to attempt to reverse the natural order 🙂

  33. Rajini Rao says:

    You’re such a diplomat, Feisal Kamil 🙂 Well said!

  34. linda colman says:

    Good news: monarch butterflies were reported in greater numbers across Northern California this year. Some say it’s due to temperature changes; some say to more milkweed being planted. Here’s the link:


  35. Rajini Rao says:

    Good to know, linda colman ! Now, if only the same were true for the bees.

  36. Fascinating information, almost none of which I knew before. That got me to imagining how that circadian-adjusted solar navigation might have evolved, and it occurred to me that even if they only evolved initially to fly in the direction of the sun (horizontally, I mean), they would still wind up flying generally south by the end of the day, just following a long arc during the day. So that could be the first step. Then later they could evolve a little “veer right” adjustment for the morning (when it’s colder) and a different little “veer left” adjustment for the afternoon. Those could occur maybe much later, maybe one at a time, to make the path more efficient.

  37. Saw the migration in Monterey, California, many years ago. There is no vision quite like trees covered with these butterflies. Those who migrate have undergone changes that make them the muscle men of monarchs so that they can withstand the rigors of such a journey.

  38. Divy says:

    Its wonderful…. specially when you see thousands of the butterflies together, it looks like a miracle.

  39. This is so very cool and informative, thank-you very much Rajini Rao I really appreciate it!

  40. Zaenal Enal says:

    this world nothing is immortal ….

  41. amit kumar says:


  42. Jim Carver says:

    Didn’t see this post at first.

    I’m surprised nobody as far as I could tell, talked about the decline of the Monarch which has been going on for several years in earnest, (actually for decades) due to loss of breeding area and pesticides. A recent Texas A & M report is very bad. Up to a 30% decline in the past year alone in Texas, and most other Western States have seen a similar collapse:

    Last year’s severe drought and fires in the region no doubt played a part, resulting in less nectar for the Monarchs as they migrated south. But estimates show that each year, millions of acres of land are being lost that would support Monarchs, either by farmers converting dormant land for crop use – mainly to herbicide tolerant corn and soybeans – or the overuse of herbicides and mowing. Milkweed is the key plant because it’s the only plant where the female will lay her eggs.”The loss of such lands is a critical factor in the Monarchs’ survival, Wilson explains…


    There’s really no comments on that post except a sad face. linda colman Your article is extremely atypical. As you will note Adrienne De Ponte said she was surprised at the number because of the past declining years. This was just one year in one area. The trend is definitely downward worldwide.

    I use the birds and the bees and yes even the butterflies sometimes as a barometer on how the environment is doing. It’s very stormy and getting lower. The only good news is we are finding out some of the things that are causing it. I submit that we pretty much knew all along, the question is…if we are able to do anything about it.

  43. AMAZING!!!! Their story is just as amazing as they look. Well, they are now in Austin, Texas so get ready they are on their way! I will enjoy them for a few more days.

  44. Rajini Rao says:

    We’ll be waiting for them up north, Marie Ysais 🙂 I have butterfly bushes in my yard (Buddleia) that are butterfly magnets!

  45. I love Butterfly Bushes! They are one of my favorite! But this year mine are not blooming yet…..perhaps this summer I can share a picture of them. I was just reading your About page and we have many of the same interests! I hope to share some recipes and gardening tips with you soon Rajini Rao

  46. Rajini Rao says:

    Wonderful, glad to meet up with you Marie Ysais . Looking forward to gardening and cooking posts from you! P.S. Butterfly bushes flower in late summer here.

  47. Some wonderful pictures here. Amazing

  48. Love the butterfly picture

  49. thank you for that picture of the

  50. Just watched a documentary on the Painted Lady and its wonderful migration from Morocco to Britain. Truly amazing

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