One-Eyed Sphinx moth, with eggs and caterpillars and pupa

2012 July 25

I was originally going to run something different today, but then I was informed that this week is National Moth Week!. Well, I can’t very well go this week without a moth, then, can I? What’s more, it should be a good one. So here goes!

This is one of several fairly large sphinx moths that was drawn to the light that I put out behind the barn on May 26, 2012. You can see how big it is from this next picture, showing it sitting calmly on Sam’s forearm.

These moths tended to sit with their heads down and their wings pointing up at an angle. I think this would mimic a dead leaf or a shaggy bit of bark if they were anywhere other than the stack of bricks behind our barn.

And like I said, there were several of them. I think this is a male-female pair (with the male on the left). Which brings up the question of whether they were all drawn by the light, or whether a few females were drawn by the light, and then followed in by the males sniffing out their scents.

Whenever they got even slightly disturbed, they would spread their wings fully, exposing the fairly gaudy eyespots on their hindwings.

From the eyespot shape and color, I think that this is a “One-Eyed Sphinx”, Smerinthus cerisyi. It’s called “One-eyed”, because a closely-related moth has a bar dividing the spot in two, making it “two-eyed”, and so the common name is distinguishing between those two moths.

So, Sam wanted to keep a couple of them in our mesh insect cage until the next day, so she could look at them at leisure. Since that is what the cage is for (and since these particular moths don’t eat as adults anyway, so it’s not as if we were going to be starving them any more than they would be otherwise), we went ahead and kept them. And the next morning, we found probably 50 of these little green, sticky eggs all over the inside of the cage. A few were a bit piled up, but most were scattered around singly.

Well, you don’t want to pass up an opportunity like that[1], so we kept the eggs safe in the cage until they hatched, on June 3 (a week after they were laid).

The hatchlings were initially curled up in a little doughnut inside the eggs, and unrolled to these big-headed green caterpillars with orange horns (the orange horns on the newly-hatched caterpillars are an ID trait for the one-eyed sphinx)

The books list a variety of foodplants for one-eyed sphinx caterpillars, and the ones we had convenient to the house were apple and aspen. So we transferred a bunch of the tiny caterpillars to a pair of jars, and offered them both kinds of leaves. They spurned the apple, and vigorously ate the aspen, so it was obvious which one to feed them. They grew fast, looking like this by June 20 (a bit over two weeks from hatching).

At this point, there were way too many caterpillars in the jars. It was getting to the point where they would occasionally attack each other, with the larger ones lashing out and smacking the smaller ones with their heads and acting as if they were contemplating cannibalism. So we released all but one of them into the aspen trees south of the house. Incidentally, they could really hang on to leaves strongly, their prolegs were coated with tiny little hooks, kind of like Velcro. This is probably an important adaptation for them, because the aspen they preferred is commonly referred to as “Trembling Aspen” from the way that their leaves shake and flutter in even the slightest breeze. If you are going to eat a quivering leaf like that, it behooves one to be able to hold on tight.

Anyway, the one we kept continued eating for about another week, and then dug down into the leaves at the bottom of the jar, contracted in length, and sweated some brown liquid for a couple of days before it finally turned into this substantial pupa by July 3:

So, the books and BugGuide all say that these moths only have one generation per year, and overwinter as pupae buried in the leaf litter, so this isn’t going to emerge until spring (and probably not until after going through a long refrigerated spell). We could have tried to keep it in the refrigerator crisper drawer until about the middle of April, but I figured the odds of it getting through the whole winter without getting a vegetable set on top of it were not good. So I took it out and buried it shallowly under the leaf litter surrounding the clump of trees west of the house. Hopefully that will do, and with any luck we may see it again at our moth-light next spring.

[1] I think everybody should try raising caterpillars at some point. It’s generally pretty easy, as long as you find the eggs or caterpillars on their food plant. The key point is to give them fresh leaves and dump out their droppings every day, so that they don’t dry out and die or get poisoned by their own fumes. Give them fresh leaves even if they have old ones left, because they need the moisture as much as they need the food. And, be prepared for a massive appetite increase and growth spurt in the week or two before they pupate.

24 Responses
  1. July 25, 2012

    awww! Adorable!

  2. July 25, 2012

    Yes, they are. They’re so cute that I’ve often wondered why there aren’t more caterpillar plush toys on the market. I would have liked one when *I* was a kid.

  3. July 25, 2012

    This is a very darling post. Thank you for it.

    Like you, I think everyone should raise caterpillars in this way and I would do this immediately, if I weren’t for the fact that I am mortally afraid of anything that is coin sized or less in circumference (and that moves).

    In other words, I am interested in creatures of this miniature size but unwilling to do the field, home and fridge studies that your family appears to contemplate and perform in the same manner as you might do your daily hand sterilizing ablutions.

    The eggs and pre-hatchling discs of eggs (moth doughnuts) were very neat.
    I also admired the horned babies that pronged out of these eggs. It’s a good thing human babies aren’t born with such identifying horns (or claws) but maybe the sight of a gluck covered newborn is sufficient deterrent against predators.

    That picture of the one-eyed sphinx rising up and then assuming various curvatures of the spine in perfect yoga –dragon fashion shows an alarming flexibility that I will never be able to achieve with my yoga instructor and I doubt my teenage sons would be this whip-lash either.

    The cannibalistic stage you describe would almost be equivalent to the teenager stage in humans I presume where a hungry teenager could walk around the dying body of his mother and merely mutter “Are we having steak for supper?”
    Yes, I am avoiding biology 20 notes again.
    I should just get older boy to look at this blog and he’d probably learn more than from that biology textbook.

    Again I am disappointed that you did not complete the entire life cycle of this insect in your fridge (even with the possibility of having a cantaloupe strike the chrysalis dead) and I am also disappointed that you did not keep all the hatchlings to explore the effects of overpopulation and sibling rivalry. These sorts of studies are done by eminent scientists all over the world and are retained in musty science novels. You could have done the good work of liberating such oddities from sealed records for the fascinated masses or ordinary bug gawkers like myself.

    Hmm… I wonder if these caterpillars are the reason why my neighbor’s Trembling aspen trees are always shaking with fright.

  4. July 25, 2012

    I am really envious of the great species diversity you have on your property! I would love to photograph some of the great critters you have profiled on your blog!


  5. July 25, 2012

    Tim, that was gorgeous. May I borrow a photo and link back?

  6. July 26, 2012

    KT: Sure, go ahead. Thanks!

  7. July 26, 2012

    Ernie: Nice macrophotos! And about the diversity, unless you live someplace like the Arctic Tundra or Antarctica, you probably have species diversity at least as good as what we have here in northern Michigan, if not better. All the parts of North America that were plowed under by glaciers in the last Ice Age have only had about 10,000 years to re-aquire an ecosystem, and we have far fewer species than what you’ll find further south. The fact that we can find all this stuff locally in spite of that, shows that you can turn up many diverse species no matter where you are. It’s mostly a question of just looking closely (and occasionally taking measures to actually lure things in, like putting out lights for moths).

  8. July 26, 2012

    Julie: Thanks! Actually, it probably would be pretty terrifying being a tree, if they were conscious. Here they are, everything in the world seems to want to eat them, and they are completely unable to actively defend themselves. I’d probably be quaking in fear, too.

  9. July 26, 2012

    Thank you so much for doing this post! My son LOVES to catch butterflies and moths, and we try to identify them. We would NEVER have known about the beautiful spotted wings unless we had seen this post. Awesome!

  10. July 27, 2012

    Off topic: Last night we came across a wolf spider the size of a Ford F-150 hubcap in our kitchen. Our oldest son, a severe arachnaphobe, suggested we photograph it for you before we let it loose (far away) outside. I decided that releasing it for a photo was going to be like letting Reggie Bush loose in your house and trying to catch him again, so we just snuck up on it, caught it and released it outside.

    It blew me away that he wanted to get you a photo of the thing. You have many, many fans. 🙂

  11. July 28, 2012

    That is good to hear, KT. Not only that he thought of getting a photo for me (which is very touching), but also that an arachnophobe preferred to just relocate a monster spider outside rather than killing it!

    Back when I first started this blog, there was another blog I was swapping pictures with (the now-defunct “Insect Picture of the Day”) where the author also started out arachnophobic. He found that, by putting a camera between himself and the spider, he could actually approach spiders without fear, and over time mostly got over his phobia. And when he mentioned this on his blog, several other people piped up that they had noticed the same thing: looking at things that they feared through a camera lens made them much braver than looking at them in real life. This might be a plan if your son would like to become less bothered by spiders.

  12. July 28, 2012

    Wow. That’s a pretty cool idea about getting over the fear of spiders. Maybe learning to identify them would help, too.

    As for the catch-and-release part, that’s my influence. I’m hedging my theological bets with some Karmic investments.


  13. Kris permalink
    July 19, 2015

    The moth you talk about is the same one that stopped at my house on Saturday. I noticed it and left it alone. It was attach to the side screen door for day. Later the second day it was gone but I noticed 16 green eggs were left. What should I do now with the eggs? Leave them or put in jar? I think I should leave them alone and becare ful opening and closing door

  14. Julie Crowthe permalink
    July 24, 2015

    Hi there. I live in British Columbia, Canada. We found one of these and have put it in our butterfly cage. Should I try to feed it anything? I think this one might be a male because it has the red eye spots…. It looks like the face of a cat or a large rodent when it raises its wings? Incredible camouflage!!!

  15. Julie Crowther permalink
    July 26, 2015

    Hi again….so, the moth that we had was a male. We tried to release it in the willow tree that just happens to reach our deck. The next morning, he found a female and they were mating…. we recaptured both of them without disturbing them in their “process”. Just now, we released the male and the female has began laying eggs in the cage we have! So exciting! We’ll keep you posted… But, when the caterpillars hatch, we’ll check in again. We’ve raised painted ladies before so are familiar with the process, but, when they turn into pupae, do you think they will hatch? Or do we just bury them under our willow tree like you did?

  16. Rachael Kellett permalink
    April 7, 2016

    Hi there we think we just found one of these whilst clearing out the outside toilet how long do they take to “hatch”?

  17. April 7, 2016

    If you have one of the pupae, they come out about three weeks after the last of the snow melts. So if you just brought it indoors, then if it emerges at all I would expect it around May 1.

  18. May 7, 2016

    Thank you for your site. I just found one on the tire of my car, male, on gulf islands in BC. It is a very beautiful moth. We moved it to a safe place. You were right to say grip is strong. Cheers

  19. Rachael Kellett permalink
    May 9, 2016

    Hi there it is now inside but not emerged I am guessing it may be a dud cocoon, shame we were looking forward to seeing it emerge. Thank you anyway for your time. ?

  20. Margaret Gardner permalink
    May 14, 2019

    I was wondering how big the caterpillars grew to be? I had a big green caterpillar fall out of a poplar tree onto me when I was sitting in the shade of the tree. It was about 2 1/2 inches long and almost as big around as my little finger.

  21. May 15, 2019

    Margaret: Yes, about the size of your little finger is about right. These are big moths, with correspondingly big caterpillars.

  22. Katie permalink
    July 12, 2019

    I found a gorgeous moth in my yard. I was hoping to send you a picture for your expert opinion?

  23. July 15, 2019

    Katie: I actually recommend sending it to, you will just need to create an account (it’s free), and then you can post your picture for the experts there to ID.

  24. Joan S Jonland permalink
    August 5, 2021

    Love these images. And great job with offering all this information. I’ve have found a one eyed in my yard this week. Really fun to find one of these beautiful moths.

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