Monarch Butterfly

2008 March 8

OK, I’ve got to do this one. Any insect-themed blog eventually has to have an entry about Monarch butterflies, Danaus plexippus. It’s required[1]. So, here we go. Last summer, S_ and Sam caught[2] several Monarch caterpillars and raised them in a terrarium. While this made it easy to watch them, the glass made it hard to get really sharp photographs.


I did succeed in photographing at least part of its tranformation from a caterpillar to a chrysalis[3]. It’s really hard to capture, the whole process only takes a few minutes and if you aren’t watching like a hawk the whole time, you’ll miss it. The caterpillar hangs itself up by its hind legs, goes inert for a while, and then abruptly sheds its skin to turn into this:


Then, quickly, before its new shell hardens, it contracts the abdomen to become this:


Then it just hangs around for about two weeks before emerging as a butterfly, with its abdomen all distended with fluid:


And, while the wings are still soft, it pumps fluid into them to unfurl them, and after fanning them for a while, it is ready to fly:


I think this particular one[4] is a male, you are supposed to be able to tell because the males have a little patch of dark scales on the hind wing (a scent gland) that the females don’t have.

Since Monarchs are migratory, and have to come back up from Mexico every year[5], the numbers we have are highly variable. Last summer, we had huge numbers, and they pretty much denuded a lot of the patches of milkweed out back. We were going to participate in the Monarch Watch, where participants tag monarch butterflies so that they can be tracked if they are caught elsewhere. But, by the time the tags were sent out, our monarchs had all lit out for more southerly regions, so we weren’t actually able to tag any. I think the program is more designed for people who live further south. Maybe we should try again sometime, and specifically request our tags to be sent a bit earlier.


[1] Maybe Monarchs are not the most-photographed arthropods in the world, but I can’t imagine what might get photographed more (except maybe fruit flies in scientific research papers). I’m positive that they must be in the top 5, at any rate.

[2] Direct quote from S_ about Sam’s response: “She said ‘Wwoooooowww!’ and wanted to touch ’em, and I told her ‘Gently!’ She can be gentle, but then I thought she’d killed one. But it came back to life.”[8]

[3] A much better sequence starts here. The people who did this one had to really work to catch it all, particularly the skin-shedding part.

[4] Actually, these photos are of three different individuals (we had about 5 total this year). It is really hard to get pictures of all of the life stages for a single individual. One of these days, I need to figure out how to interface a camera with my computer for time-lapse photograpy, and just have it take a picture every minute or so.

[5] It’s funny how butterflies never seem to get classified as an invasive species. In the case of Monarchs, they’d probably be considered a serious agricultural pest if milkweed was actually a marketable crop, instead of being a toxic plant[6] that most farmers would be just as happy to be rid of.

[6] If cattle or horses are stupid enough to eat much of it (it tastes horrible), it can make them really sick[7]

[7] Big plus for the Monarchs: by eating a toxic plant, they themselves can become toxic, and if, say, a Bluejay unwisely eats one, well, it’s projectile vomiting time!

[8] Evidently, Monarch caterpillars are known for being fairly tough and tolerant of abuse. Probably because, when your main defense is tasting bad, it is a good thing to be able to survive being mauled long enough for your attacker to realize that you taste bad.

4 Responses
  1. March 12, 2008

    Beautiful and informative. Thank you for sharing these!

  2. September 24, 2008

    Very good! Make a page all about it and put in their charactistics and if they are an arthropod or not and tell people all about it/them. Like where they live and stuff like that… their lifecycle could be useful too… Well… Good Lucky!

    Yours Truly,
    Vanessa L.

  3. March 28, 2010

    I run a free, drop-in open studio for those pursuing better mental health using art as a therapeutic device. I study psychology and english at college at the same time, just to keep up with the participants! I often use a metaphor for my team leaders, or a struggling artist, about not cutting the pupa, how it hurts the butterfly to try to “help” it at certain points, that some pain and struggle accompanies us in everything we do. The trick is to know when to step in, in other words, and to what degree. So, is it in fact true, to cut the pupa, to help the butterfly have an easier time of it, you would actually kill it? Or make it into a vicim easily picked up by a passing crow? I’m assuming yes, but I’d like to know the full science of why it’s bad.

    Thank you,
    P (I’ve attached your bug site, and blog to my favorites. Excellent source of clearly organized and wondrous information, good job!)

  4. March 29, 2010

    Pam: Yes, it would be almost certain to do more harm than good to “help” a butterfly out of its chrysalis. The butterfly is in a very fragile state, with a soft exoskeleton, at the time it emerges from the chrysalis. The chrysalis is evolved to have particular weak spots that will pop open easily under pressure from inside, but there is nothing accessible from the outside. Any attempt to assist will tend to crush, pierce, or tear delicate body parts. And, if one tried to do it too early, the unfinished butterfly would still be in a partly liquid state, and it would kind of leak out.

    You might be able to make a case for pulling off the last bit of the chrysalis once the butterfly has mostly emerged, but even that is dubious. I’ve never seen one get hung up on the chrysalis. The only problem I’ve seen is that, if they emerge in a chamber (say, a small jar) that is too small to spread their wings fully, then the wings dry curved, wrinkled, and nonfunctional. So, as far as analogies go, make of that what you wish.

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