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Bagworm Moth Bags


If you find a tiny (1/2″ long) bundle of stick-like pieces of vegetation clumped together into a “bag” that is attached to a structure, you have discovered the abandoned home of a bagworm moth larva, and the overwintering site of bagworm moth eggs. The bags consist of parts of the vegetation that the larva was eating and then bound together with silk.

In the spring, the eggs hatch and the larvae all leave and build protective cases, or bags, for themselves, inside of which they live while feeding, growing and molting throughout the summer. As the larvae increase in size, they increase the size of their bags. Eventually the larvae attach the bags to branches, trees, etc. and pupate within them. Female bagworm moths are wingless, and thus are confined to life within a bag for their entire lives. Upon emerging, adult male bagworm moths seek out the females and mate with them before perishing. After laying eggs inside their bags, females exit and die.

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10 responses

  1. Alice Pratt

    Nature is amazing!

    December 22, 2016 at 8:18 am

  2. Yet another aspect of life for which I am grateful — I was not born a female bagworm moth!

    Happy Solstice!

    December 22, 2016 at 8:42 am

  3. THANK YOU!!! For years I’ve wondered what these are!!!

    December 22, 2016 at 10:12 am

  4. Kathryn Connell

    From a human perspective, that sure sounds like a sad life. But it obviously works for them!

    Happy Holidays Mary and to all your readers.

    December 22, 2016 at 11:10 am

  5. Alan M Stoops

    I have long wondered why a species would have wingless females and winged males. It seems like the reverse would be more effective at spreading the population. Wingless females aren’t going to lay their eggs very far from where they hatched.

    December 22, 2016 at 12:04 pm

    • I have wondered the very same thing, Al. I know of several species where this is the case, and I haven’t figured out the advantage yet.

      December 22, 2016 at 2:16 pm

  6. Chris

    Hi Mary,
    I just received your new book, which I ordered for Christmas gifts. This is an incredible, stunning work, Mary. Congratulations! I’m going to order one for myself, and I look forward to a new nature discovery every day next year. Thank you!

    December 22, 2016 at 12:11 pm

    • Thank you so much, Chris. I am thrilled that you like Day by Day — it was five years in the making! A very Merry Christmas to you!

      December 22, 2016 at 2:16 pm

  7. melody masi

    Thank you for all your posts, I enjoy sharing them with my grandson and others who have an interest in the beauty of the natural world. A Merry Christmas to you and your family.

    December 23, 2016 at 10:07 am

  8. Susan

    Thank you for explaining one of the mysteries of my life. And thank you for sharing Naturally Curious – a light in my life. Merry Christmas to you and yours.

    December 25, 2016 at 4:09 pm

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