Common Aspen Leaf Miner

2015 September 30

Sam found this interestingly-mined aspen leaf while we were walking in the woods on June 8, 2015.

This long, squiggly track is characteristic of the Common Aspen Leaf Miner, Phyllocnistis populiella. It started shortly after hatching as an egg at the small end of the trail:

and after working its way all over the leaf surface, it evidently popped out and curled up an edge of the leaf to make a shelter to pupate in. I think we can see the caterpillar’s head poking out just a bit.

As you might guess, these can get extremely common, and tend to favor trembling aspen and balsam poplar as their host plants. By mining the inside of the leaf like that, they can eat the actual nourishing part while leaving the upper and lower skin of the leaf in place as camouflage and general protection from the elements. These are distinct from the Aspen Leaf Blotch Miner moths that we also have around in tremendous quantities, but that make a localized, blotchy leaf mine instead of a long, serpentine trail through the leaf.

In extreme infestations, these types of leaf miner can seriously reduce the ability of the tree to do photosynthesis, and can stunt their growth. Since aspen is widely used for papermaking and for wood products like oriented strandboard[1], it has enough economic value that the miner moths are considered pests.

[1] Aspen isn’t much of a lumber tree, because the wood is not all that strong and rots quickly. But, on the other hand, the trees grow like crazy and thrive in colder climates where the land isn’t much good for other kinds of agriculture. So, it would be nice to have some way of converting aspen into a usable construction material. Which is why Oriented Strandboard was invented. This is wood chips pressed flat and glued together to make large, strong sheets that make good sheathing material (and is somewhat cheaper than plywood, although it is hard to drive nails into and is kind of annoying to work with sometimes). Aspen is soft and easily made into wood chips, and the addition of the adhesive helps protect it from rotting, and so aspen is widely used for making this material.

2 Responses
  1. Anne Bingham permalink
    September 30, 2015

    Hmm. At first I thought that oriented strand board was the same as particle board, but further googling shows that while it’s manufactured along the same principle, strand board is stronger. Particle board is sawdust and wood chips, strand board has machined chips aligned for strength. Love learning new things!

    Also, it was fun to trace the leaf miner’s route. Did you keep the leaf to see what emerged?

  2. September 30, 2015

    I did keep it, but nothing ever came out (or if it did, it got away. These leaf miners are pretty tiny as adults).

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