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Keeping A Dead Leaf Partly Alive

If you look on the ground these days as yellow Trembling and Bigtooth Aspen leaves are falling, you may notice that small splotches of green remain in some of them.  These chlorophyll-laden patches are usually found near the bottom of the midrib of the leaf.  If you open the pocket of tissue at the base of the green section, it’s highly likely you will find a minuscule (2 mm long) translucent caterpillar (a microscope may be necessary to detect it).

The caterpillar (larva) first bores into the stem, or petiole, resulting in a swelling. When it reaches the leaf blade it makes an elongated blotch between the midrib and the first lateral vein. The larva is capable of secreting a chemical which prevents the natural deterioration of the leaf.  As a result, chlorophyll is retained in this area and photosynthesis continues to take place, providing the larva with food.  The leaf-mining larva (Ectoedemia sp.) will pupate over the winter (outside the leaf) and emerge next spring as a very tiny moth which will feed on the honeydew secreted by aphids. (Photo: Mined Bigtooth Aspen, Populus grandidentata, leaf)

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12 responses

  1. acadia94@zoho.com

    Mary,

    This is Fascinating! Can you provide some more details on the timing of the cycle? I assume the larva enters the leaf while it’s still attached to the tree? How long does the leaf remain attached before it drops? How much longer does photosynthesis occur within this island of chlorophyll? When does the larva finally leave the leaf to pupate? Does it travel any distance from the leaf before it pupates (or is it attached to the leaf?).

    As a Teacher Naturalist with Mass Audubon, we are currently leading school programs about trees and I’d love to mention this interesting case.

    Thanks for all the wonderful posts you share!!

    Susan Thomas

    >

    October 30, 2019 at 7:36 am

    • Hi Susan,
      I’m afraid you know as much as I do about this phenomenon! If you can find the answer to any of your questions, I would love it if you would share them with me. So sorry not to be of more help to you – they are questions I’ve had as well!

      October 30, 2019 at 6:25 pm

  2. LG

    I have noticed this leave coloration over the years, often collecting a few samples, because of their unusual beauty and am fascinated to learn of the little creature that is responsible !

    October 30, 2019 at 9:57 am

  3. Char Delabar

    >

    October 30, 2019 at 10:16 am

  4. Very cool! I’ve seen so many of these this year!

    October 30, 2019 at 10:35 am

  5. Kay Byram

    Dearest Joc,

    You’ve heard the phrase, “Nature finds a way.”? Well, in this case it really does by allowing a very small member of it to survive. The host organisms are the Trembling Aspen, also known as the Quaking Aspen, and the Big-Toothed Aspen. According to https://www.inhs.illinois.edu/research/vmg/qaspen/ : “Quaking aspen has one of the widest distributions of any tree in North America. This aspen can be found from northern Alaska to Newfoundland, south to Pennsylvania, Missouri, northern Mexico, and lower California. In Illinois, it is recorded from 38 counties and is most common in the northern half of the state.” You may have actually seen one even though you live in the southern half of the state. So on your walks you and Mom can be looking for yellow leaves with little green spots near the stem. Let me know if you see any!

    I love you to infinity and beyond, Nana

    October 30, 2019 at 10:39 am

  6. C.F. Holland

    Terrific, fascinating but I DON’T CARRY A MIRCOSCOPE FOR MY WALKS. Perhaps a strong magnifying glass? Sherlock HOLMES TO THE R,ESCUE !

    October 30, 2019 at 10:48 am

  7. Susan Holland

    Wow! That is very cool! Who would have thought that this was the reason for those green splotches? Not me, that’s for sure. Something new learned again from your blog! Thank you!

    October 30, 2019 at 11:51 am

  8. Alice

    So very interesting.

    October 30, 2019 at 1:04 pm

  9. Pam Jackson

    Wow, that is fascinating! Didn’t know about that one. Does it affect many leaves or just a few in an area?

    October 30, 2019 at 6:58 pm

    • Good question! I usually notice quite a few under a given tree, but don’t know anything about the distribution of this insect!

      October 31, 2019 at 3:01 pm

  10. Toni Callahan

    Hi, Scott,
    I couldn’t resist sending this along to you; it’s so interesting, and I thought you, too, would find it so! (Of course, you probably already know all about this stuff, but I thought you might appreciate it.)
    Best,
    Toni

    November 1, 2019 at 9:17 pm

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