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Polyphemus Moth Cocoons

12-15-17 polyphemus cocoon2 IMG_4455The Polyphemus Moth is a giant silk moth, a member of the Saturniidae family which includes some of the largest species of moths. Giant silk moths derive their name from both their size as well as the fine silk they use to spin the cocoons which serve as protection for the pupal stage in their life cycle.

Most Polyphemus Moth cocoons start out attached to a tree branch, although some are spun among leaves or grasses on the ground (see pictured cocoon). They are oval, roughly 1 ½” long and nearly an inch wide. Cocoons in trees are susceptible to attack by squirrels and woodpeckers, whereas mice are the biggest threat to cocoons on the ground.

The moth overwinters as a pupa inside the cocoon. Unlike most other giant silk moths’ cocoons, the Polyphemus Moth cocoon lacks an escape “valve” at one end. In order to emerge (as an adult) from the cocoon the summer after it spins it, the moth secretes an enzyme that digests and softens the silk at one end. Then it moves about the cocoon in a circular pattern, tearing the softened silk with two spurs located at the base of each wing on its abdomen. Eventually it escapes  by splitting the silk and pushing the top up.

13 responses

  1. Alice Pratt

    So informative, Mary…what an amazing cocoon & beautiful moth!

    December 15, 2017 at 8:43 am

  2. Dan Poor

    Not related to today’s post, but Where have all the squirrels and chipmunks gone? I have seen one grey squirrel gleaning under a feeder before the snow covered the ground. Maybe a chipmunk or two. No red squirrels that I recall. I know we had a resident fox family this summer, but I find it hard to believe that they were this thorough. There is some evidence of squirrels in the woods bordering pasture land but none around the house.

    December 15, 2017 at 9:03 am

    • I haven’t noticed this phenomenon, Dan. Quite the opposite, actually. Chipmunks have gone underground here, and with the enormous crop of acorns, etc. this fall there should be a boom in squirrel (and other rodent) populations…so keep your eyes open next spring!

      December 15, 2017 at 9:47 am

      • Dan Poor

        I’m sure that there will be plenty of squirrels back in the spring, but it is certainly unusual to not have them around the feeders. Maybe they realize that they are almost squirrel proof (Ha!). Or maybe they’ll be back when they exhaust whatever stashes of acorns they managed to accumulate and then find.

        December 18, 2017 at 8:27 am

  3. Jane Marshall

    Absolutely amazing. I would never have known about this and so many interesting facts, were it not for you excellent daily reports. Love these updates on our natural world. Many thanks,

    December 15, 2017 at 10:18 am

  4. Kathryn

    The facts and descriptions you come up with, Mary, are so incredible. Even more amazing is all the adaptations creatures have made to survive.

    December 15, 2017 at 10:48 am

  5. Frances Henry

    Mary, greetings, We usually contribute this time of year. I do not see the link to your website. I also could send a check if you might prefer one instead of an online donation….Thanks for your hard work. Fran and Walter

    On Fri, Dec 15, 2017 at 8:27 AM, Naturally Curious with Mary Holland wrote:

    > Mary Holland posted: “The Polyphemus Moth is a giant silk moth, a member > of the Saturniidae family which includes some of the largest species of > moths. Giant silk moths derive their name from both their size as well as > the fine silk they use to spin the cocoons which serve as ” >

    December 15, 2017 at 11:19 am

    • Thank you so much, Fran and Walter. If you go to my blog,, and click on the yellow box that says “Donate” it should take you where you can do so. I will resume posting a donation paragraph at the end of my posts in 2018 — readers were just so generous to my daughter’s plight this summer that I haven’t felt I could ask for donations. Thank you so much for thinking of me.

      December 15, 2017 at 2:21 pm

  6. Laurie Spry

    I echo what others are saying about the amazing facts you teach us. but also the incredible diversity and variety of life and adaptations right under out noses. Thanks SO much!

    December 15, 2017 at 5:42 pm

  7. Shelagh Smith

    Just about impossible to find a cocoon, bravo Mary! I, too, have really enjoyed all your posts.

    December 16, 2017 at 4:29 am

  8. I have a cocoon found on tamarack: white, correct dimensions. We suspect (or simply hope) it is Hyalophora columbia, which would be grand as they are so rare and not reported in Vermont. I wish spring was not so far away. A couple scientists in Boston are even waiting for it to eclose. If it is, you’ll hear me crowing far and wide.

    December 16, 2017 at 10:26 pm

    • It certainly sounds like it could be H.columbia! Please let me know if it is! Hope winter zips by for you!

      December 17, 2017 at 8:48 am

      • 🙂 Me, too!

        December 17, 2017 at 8:49 am

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