Big Brown Moth

Green Caterpillar: Antheraea Polyphemus

This is a follow-up to the Big Green Caterpillar post from last August. My wife had determined that this caterpillar was probably Antheraea Polyphemus.

We found three cocoons from these guys around our yard last fall. One was attached to a board leaning against the house and two were wrapped up in leaves under trees. This spring, it didn’t look like one of the cocoons on the ground had made it. We put the other inside one of our daughter’s “bug catchers” so we could keep an eye on it, and today it emerged!

Brown Moth 1: Antheraea Polyphemus
Bigger: 2816 x 2112

It’s so miraculous, this metamorphosis. He wasn’t ready to fly at first, so we got a good look at him and several good pictures. Such a crazy life-cycle: starting as a crawling thing and then spending the winter in a cocoon to emerge as a flying creature in the spring. They don’t eat in their moth form and live less than a week. The male will fly for miles to find females to mate with.

You can see more detail in the larger images linked from here. The large, bushy antennae say that this one is a male. It may be hard to tell from the photos, but the spots are translucent.

Brown Moth 2: Antheraea Polyphemus
Bigger: 1218 x 1350

It was pretty cool to see both sides of the transformation and fun and exciting to share this with our daughter. Before long he took off and fluttered away. Makes me think about all of the ways that life plays out around us. If not for the happenstance of seeing that big green caterpillar last fall, we would have been oblivious to this drama playing out.

Brown Moth 3: Antheraea Polyphemus
Bigger: 1803 x 1317

It just amazes me that this works at all. It seems so complicated. But it’s wonderful.

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46 thoughts on “Big Brown Moth

  1. Watching this process as a child is one of the main reasons I ended up a biologist. I’m no less fascinated and awed by it now than I was at six.

  2. I ran across the moth form a few years ago, and just recently my boyfriend stumbled upon the caterpillar. I suspected they were the same, and a little googling brought me to this post. Now I know what it is. Thanks for posting! GREAT pictures.

  3. I found the same kind of caterpillar, and watched it spin the cocoon last winter. Just last night it hatched. I agree it was very cool to see what would happen to it.

  4. OMG at this very moment one of these things is chilling in the back of my boss’s gallery! It’s huge! It’s as big as my hand! Everyone is saying ” let it chill, don’t touch” so I took some pictures with my hand near it instead. Holy crap, I closed the door to the back that thing is scaring me – even if he won’t hurt me, he’s the biggest bug I have ever seen in person!
    (My apologies to any biologist who will tell me “Moths aren’t bugs” I don’t know if they are or not)

  5. I found one of these big green caterpillars and don’t know where to put it. Any help anyone?

  6. Just found one near East Troy, WI. My grandchildren will use it for a science project and turn it loose when it hatches.

  7. Just found one on my porch in northwest Florida looks neat but those hairs look dangerous to me haha everytime I get real close they look Like they come out more.
    Wish I could add a picture but it looks exactly like that one
    Hope it makes it’s cocoon here would be cool to watch

  8. we found a huge white caccoon las summer and it never had anythng come out.. until today.. feb 9 2011 and its super cold out here in mn so now i am wondering what i should do with it. we thought it was a bad caterpiller and just left the jar on the counter. i was cleaning and saw something move out of the corner of my eye, scared me a little. but i couldnt believe how big and ugly this thing was! the body is about the size of my thumb and all i can say about the body is eww. the wings are neat- they have this pretty blue circle around the rings and the edges of the wings look like tree bark. Anyone know what i should do with this thing??

  9. Hi!!!! iam so glad to have found this! My students found a caterpillar like this this morning…we think it may have fallen out of a pecan tree. This afternoon it started wrapping itself up in leaves so I hung the leaves up- as if it were making a crysalis. Is that ok/ Or does it need to be lying flat? How long does the process take?


  10. Hi,

    So glad to see these photos. That’s exactly what’s been on my front wood porch for two days.

    This huge brown moth which sits high on its legs and has fuzzy antenna.

    How sad it won’t live long. I didn’t try to pick it up and relocate it, as I sometimes do with insects. Had no idea what to do.

    Guess I’ll just leave him undisturbed.

    Thank you for the information.


  11. hiii!! we found one of these little cretures at the beach a few days ago so we have him in a llittle plastic container it seems like he wants to cacoon but all he is doing is wiggleing aroun.When we first found him his suction cups were sticking right to us now there not doing anything and he is jjust rolling around.He is not eating i was wondering if they dont eat leaves and eat something else so i was wondering if u knew?and they cacoon should we just leave him on the ground cuz it wont go on a branch does he jjust curl up in leaves thanx for helping marjorie

  12. I was so excited to find this! A whole group of teachers as well as myself (the center director) and about 15 3-5 year olds found one of these critters in our playground Friday. We did want to “take him in” I called it “The very hungry Caterpillar” but it was so odd looking and sooooo big! Glad to know what it was as we thought it was an alien creature ;-)

  13. My daughter and I saw one of these green guys today (Cleveland, oh area) I had never seen such a large caterpillar! It was amazing. We were in no position to take it with is anywhere but we did move it off the sidewalk to a more wooded area in hopes of avoiding it getting walked on or run over accidentally.

  14. I just picked one off the trunk of my Linden tree.It’s the biggest caterpillar I have seen.I put some leaves in the container,but it went to the top corner and is starting to spin a web. I guess I’ll put it somewhere for the winter, and see what happens. Would love to see a big moth emerge! Have already had the experience with Monarchs, but this will be different. Thanks for the pictures. My grand kids are really freaked out by the size of this thing!!

  15. I just found one of these in the country in LaCrescent, MN. I want to take it to school and see if it will hatch for my first graders. Any suggestions would be greatly appreciated.

  16. I forgot to mention,I am in Quebec, Canada. Seems a little North for these guys! Hope it won’t hatch in February….our coldest Month!! Inge

  17. I found one today in Torrington, CT. We put it in a plastic cup and now a few hours later it is spinning a cacoon I think!

  18. Found one in Spartanburg south Carolina 12:53 am, I was getting gas and seen him creeping along on my moms pants leg! I guess he was just hitching a ride to the nearest tree lol! I put him in a bag and by the time I got home to show the husband he was already spinning silk so I went outside and let him go find a safe place on a huge oak tree, hope he’s gonna b pretty, I never seen anything like him before but nature is truly amazing!

  19. Thank you for posting this! I was out camping last weekend and I saved a fat ole green caterpillar like the one you photographed, he was baking in the sun trying to get under some rocks, so I moved him to a shady tree. I wasn’t sure if he was going to be a moth or a butterfly, but you sure cleared that up for me. Thanks again!

  20. My neighbor found one of these amd gave it to my son. We put it in a small fish tank and when we looked at it in the morning it was spinning a cacoon. Does anyoneknow if you can keep them inside until their metamorphous?

  21. My 5 y/o daughter and her friends found one of these outside today (Ontario Canada). At first I thought it was a tomato hornworm, but there were no horns. Thank you so much for posting this, I’m going to try to keep it and donate it to her kindergarten class. It would be neat for them to watch it and compare it to the monarch butterflies they get every year.

  22. I just found a big dead one near my car today! I posted a pic to Facebook and my friend then sent me this link. I was amazed at how pretty is was before it died!

  23. Yesterday, the lunch lady and some first graders at my daughter’s school in San Jose, CA found this enormous caterpillar. They took it back to the classroom to “investigate.” They had the opportunity to touch and hold it. The teacher put it back later that day. Today they wrote about and drew the caterpillar in their journals. They had fun reading their stories to each other.

  24. Found one of these near Osoyoos, British Columbia Sept 7 and decided to investigate it’s origins. Found this site and decided that the one I found was indeed the same. I suspect it is not common nearer to the west coast. Quite an awesome sized caterpillar. Anyway, I left it to go on it’s way, suspecting that it was searching for a location to spin it’s cocoon.

  25. Found one curled up in a stone driveway at our friends camp while cutting some trees for firewoo. Florence, NY. We put it in a jar with tinfoil top with holes. By the time I got home it had crawled to the top corner and spun a brownish cacoon. We thought it was a Hummingbird moth caterpillar. Glad to know what it is. I opened the top of the tin foil and have it next to my birds with sunlight and nice warm breeze.

  26. We just found the same caterpillar, my 6y/o and 4y/o girls are quite interested in him/her. So we decided to but it in a jar. It is spreading what looks like hair on the side of the jar. I am assuming it’s the staring of it’s cocoon. I’m hoping the jar will suffice space wise. If you have any ideas on what could make it a better experience please don’t hesitate to e-mail me @

  27. Just saw one of these big green caterpillars here in Hudsonville Mi, my daughter said to kill it, I said no! It was really neat to look at. We took some pictures. Im glad I let it live, after all it is one of Gods creatures. SEPT 13-2011.

  28. Just found one at our school in Fuquay Varina, NC. Seems like it was starting to make it’s cacoon on the underside of a picnic table, so I relocated it to make sure the students wouldn’t mess with it. Hope it’s there tomorrow, and that we can watch it transformation.

  29. After soccer practice tonight, while my kids where walking their friend home, my oldest daughter found one of these beautiful caterpillars on the sidewalk. We were excited and put it in a mason jar. I decided to find out what it might turn into. I have never seen anything like this while growing up in WI and now living in WA. It looks like it is already making a cocoon. We can’t wait to see what will happen next.

  30. Hi All! This is to everone, teachers and do-gooders alike. Please remember, that the best (and safest) time to release these moths is at night, after the birds have gone to bed. If they spot him flying about, he will become a quick meal in front of the kids. They are so large – they become easy targets. There is still a small risk of bats at night, but we want to give them the best chance we can. His main job is to find a mate so this wonderful process may start over again! This is our second one – and I have to wonder if my first fellow is this moth’s parent :) Cheers!

  31. I spotted the same large moth tonight on our front door while watering the grass. It is really beautiful! I hope to get a picture of him. I live Ontario, Canada.
    With the light shinning on him, the translucent spots look like diamonds.
    It would be interesting to see if I spot another one of these in my lifetime.

  32. hello just found one of these today and it was sitting on door frame to garage couldnt believe how big it is never before seen one ! i am located in port colborne,on canada my daughter was afraid to go into garage lol seemed that he cannot fly but maybe cause he just came out of cacoon ??? we will let him go tomorrow night :) took some great pics of him he is beautiful !

  33. rescued a female possible polyphemus?moth off a hot chesapeake,virginia sidewalk @ 10 am,7-16-12.put in my bag and 6 hours later there are 6 eggs in the bag.know the life cycle is probably over but how and where do i transplant the mother + eggs?

  34. We live in a old, small apartment complex, but the diversity of life here is amazing. We have raised a couple of generations of black swallowtails, and it’s been a great process. This morning, on our walk, we stumbled upon 2 polyphemus moths mating right on the sidewalk! My 4 year old was confused (and admittedly, the position looked awkward!). I had my hands full: stroller, dog, bag, etc. or I might have been inclined to grab them, and hope for eggs in my little window garden…but then again, if I intervened, they might not have gotten to finished. So keep your fingers crossed for a couple of polyphemus moths in Hamilton, NJ. Your post here helped confirm my ID. Thank you for posting your wonderful story and photos.

  35. My kids found one of these today on our porch. We are in Windham, Maine. I keep going outside to check on it. We are totally fascinated by this thing! Can’t get over how big it is!

  36. Yesterday, we found one of these caterpillars on our door step. We Googled “big green caterpillar” and this was the first thing that popped up. Thank you for sharing your story. We have put “Fontleroy” in a large jar, and this morning, I found him wrapped in a cocoon. I am going to do more research to see when he will emerge as a beautiful moth. I’d like to know when to be ready for him. Thanks again for this page!

  37. We found the caterpillar side of this guy yesterday in our lawn! I was so taken back that I showed it to my husband and kids. The young fella is beautiful! Thank you for sharing this information. I want to go find it now and bring it inside to watch it work it’s miracle. So far we can’t find it again. We are in Sturbridge, Massachusetts.

  38. Today my daughter found our “little” guy taking a stroll on the sidewalk. We brought him home and put him in our bug cage. Hoping we are lucky enough to see a cocoon like the rest of you. The girls want you to know we named him Grinky. One wanted Green and one wanted Stinky.

  39. My daughter found one today crawling in her fairey garden. We took that as a gift from the fairey’s… Hope to enjoy it’s metamorphisis!

  40. We found this big green beauty hanging onto our four-wheeler in Mineola, Texas. Thanks for your post. We’ll put him back and let nature take it’s course.

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