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Case-bearing Leaf Beetles Eating & Growing

8-1-16 case-bearing leaf beetle 110It’s not every day that I discover a species I’ve never seen before, but when it comes to insects, it happens regularly.  Rarely, however, are they as interesting as the Case-bearing Leaf Beetle I observed on a blackberry leaf recently.  An oval, brown, stationary case about ¼” long was at a 45° angle to the leaf it appeared to be attached to it.  Upon closer inspection and with a bit of probing, a head and six legs appeared at the leaf end of the case, and the case began to move.

How its case was created is as, or more, interesting than the beetle itself.  The adult female Case-bearing Leaf Beetle lays an egg and wraps it with her fecal material as she turns the egg, until it is completely enclosed.  Once hardened, the feces create a protective case for both the egg and eventually the larva.  When the egg hatches, the larva opens one end of the case, extends its head and legs, flips the case over its back and crawls away.  As the larva eats and grows, it adds its own fecal material to the case in order to enlarge it.  Eventually the larva reseals the case, pupates and then emerges as an adult Case-bearing Leaf Beetle.  If it’s a female it then prepares to mate, lay eggs, and recycle its waste.

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22 responses

  1. Wallie Hammer

    What does the beetle look like without the case?

    August 1, 2016 at 7:42 am

    • The larvae of many species are light orange and have long abdomens. The adult beetles typically are quite colorful, often black and orange.

      August 1, 2016 at 7:58 am

  2. Alice Pratt

    Wow! Taking recycling to a whole “new” level! I think we should not follow in it’s footsteps, however!

    August 1, 2016 at 8:04 am

  3. Clyde A Jenne

    The ultimate recycling.

    August 1, 2016 at 8:11 am

  4. Nature is so ingenious! Considering how this may have evolved…

    August 1, 2016 at 8:12 am

  5. That is really interesting Mary – the lives of little beings are so fascinating, I wonder what stories they tell of us – thanks

    August 1, 2016 at 8:15 am

  6. Dianne Rochford

    How AMAZING!! I’m a bit confused……At one point you say that the larva emerges, flips the case over its back and walks away and then you say that the larva continues to add to the case and eventually pupates there until adulthood.

    Thanks for clarification.

    :-), Dianne >

    August 1, 2016 at 8:42 am

    • Hi Dianne, I’m not sure what you are confused about, as you have it exactly right! The larva lives inside the case, enlarging it as it grows. When the time to pupate comes, it seals the case. It then pupates and the adult beetle exits the case.

      August 1, 2016 at 9:19 am

  7. Janet Andersen

    Truly amazing. The insect and you. Most people would never notice this amazing insect or think it was a bit of bird poop!

    August 1, 2016 at 8:43 am

  8. Janet Watton

    Utterly fascinating! Just a “curious” question: how, with this hard poop housing, do they mate?!

    August 1, 2016 at 8:53 am

    • Janet, they pupate inside the case, then emerge from it as adult beetles and mate, minus the case!

      August 1, 2016 at 9:12 am

  9. Louise Garfield

    Thanks for this fascinating post !

    August 1, 2016 at 9:00 am

  10. We could benefit from paying attention to the little creatures that are so important. Like this post.

    August 1, 2016 at 10:15 am

  11. Viola


    August 1, 2016 at 11:17 am

  12. I think I have seen these years gone by now.
    Interesting story on how this insect makes it all happen & then starts the process all over again.
    I am really curious & somewhat concerned about the plight of the monarch butterfly between Mexico & Vermont, my neck of the woods…
    Last year for the first time in my 17 years on the mountain & so far this year, not a single sign of the monarch or it’s caterpillar stage that I know uses the milkweed plant as it’s host.
    This season, many if not most my milkweed leaves have been thoroughly chewed on, but once again no sign of any monarch caterpillars or their eggs attached to the undersides of the leafs.
    Today is Aug. 1st, so I still remain hopeful they ( Great, Great Grandchildren ) make it up here this season…
    Bill Farr

    August 1, 2016 at 11:38 am

    • Hi Bill,
      As I understand it, last winter’s population in Mexico was an improvement on the three previous winters, but this March there was a terrible sleet storm in the Transvolcanic Mts. in Mexico, and it killed multitudes of monarchs, so they are guessing that numbers this summer, and this fall’s migration, will be down. In addition to habitat and GMO, climate change and the weather it’s causing seem to be a major factor…

      August 1, 2016 at 2:08 pm

  13. Laurie Spry

    You couldn’t make these things up, could you? Truth is always stranger (and more fascinating) than fiction!

    August 1, 2016 at 4:48 pm

  14. Now THAT is amazing! 🙂

    August 1, 2016 at 5:00 pm

  15. Dianne Rochford

    What an amazing creature. But I’m asking for clarification…you say the larva emerges and flips back the case and crawls away and then the larva eats and grows and adds fecal matter to the case and eventually goes inside to pupate. Don’t quite understand the process if the insect crawls away………


    :-), Dianne >

    August 2, 2016 at 5:15 pm

    • The larva crawls away with the case on its back and it remains there until the larva seals it up and pupates…does that help?

      August 2, 2016 at 9:00 pm

  16. Kathie Fiveash

    Amazing! And this summer I have lots of monarchs on my milkweed on Isle Au Haut in Penobscot Bay in Maine. First time in the last few years. So I have felt hopeful.

    August 3, 2016 at 1:00 pm

    • That is great news, Kathie! I read about a severe sleet storm in Mexico last February, and that they were predicting fewer monarchs this summer.

      August 3, 2016 at 3:16 pm

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