Have you notices that sometimes, groves of Aspen trees start off looking green, but then start looking silver? You’re seeing the evidence of Aspen Leaf Miners on a large scale.
What you’re seeing are the tracks left by the larvae of a group of Moths in the Lyonetiidae or Gracilariidae families. There are at least 300 species in these families in total, so it’s often really hard to tell who’s actually doing the damage. Some of these species go after specific trees, like Magnolia or Oak, but they all do the same thing: they eat away at the surface layer of the leaves. On Aspens, it’s almost certainly Phyllocnistis populiella, a Gracilariidae family moth.
There’s one of these larvae in the photo at the top. Look on the lower left-most leaf. See the small white thing in the middle of the bottom half of the leaf? That’s an Aspen Leaf Miner at work. They feed on the contents of epidermal cells on both top and bottom surfaces of aspen leaves, leaving the photosynthetic tissue of the mesophyll intact. That’s a complicated way of saying they make a mess but don’t generally harm the tree.
A fascinating life cycle
The life cycle of this moth is kinda cool. They hibernate as adults, and emerge just as Aspen trees are leafing out. They feed on nectar produced by glands at the base of the leaves. They mate, and lay one egg per leaf, folding a small bit of leaf over to protect the egg until it hatches. Take a look at the photo to the right and you can see the fold where the egg hatched out.
The larvae breaks out of the bottom of the egg and start eating the surface layer of the leaf. That line they leave behind? Larvae poop! When it’s time to pupate, they just make a little silken cell and stay on their leaf. They hatch out as Moths in late summer, just in time to find a place to hibernate.
Meet some of the other cool critters of K-Country here!