Looks like someone has been drawing mazes or abstract designs on these leaves, doesn’t it? Want to know who the artist is? The artist is actually a baby moth! Now that’s what I call a talented youngster lol.
This pretty design is made by a tiny moth called the Common Aspen Leaf Miner, Phyllocnistis populiella (taxonomic family = Gracillariidae). Technically it’s the caterpillar, or baby moth, that made that artwork, as the adult moth doesn’t feed on leaves. These moths are part of a specialized group of bugs called “leaf miners” that have evolved to hide their larvae (aka baby bugs) within leaves of the actual leaf they are eating. So sneaky! Who wouldn’t want free meals to come with their housing?
Some leaf miners are beetles, some flies, some herbivorous wasps (“sawflies”), and some, like this one, are moths. The serpentine patterns on the leaf are the tunnels that the caterpillar has chewed through already. And not all leaf miner artists are created equally! The pattern, or lack thereof sometimes, varies a little between individuals and sometimes vastly between different species.
Normally, a few of these Common Aspen Leaf Miners don’t cause that much overall damage to healthy full-grown trees. They only lay one egg per leaf and don’t lay eggs on every leaf of the whole tree. However, if there is a bad outbreak of these little guys, like some much more northern states have had recently (like Alaska), they can severely stunt or possibly even kill a tree. At this point, there are not enough leaves to go around, with multiple babies on each leaf, and on all the leaves. It can be too much for the tree to handle. Kinda like when you live in a tiny apartment and all your family comes to visit, use your stuff, and eat your food… Thankfully, it looks like I just have a very small population of leaf miners on the property as I’ve only found trees with a couple leaves here and there with miners.
A large part of keeping my leaf miner population under control is likely due to predators eating the juicy little caterpillars (despite being hidden within the leaf). The aspen seedling (=baby tree) I found with the leaf miners shown in the pictures was actually covered in ants, not just leaf miners. Ants are smart. Many of them are predators and hunt anything soft-bodied they think they can eat. The ants found some of the leaf miners on this aspen seedling and appeared to be looking for more to bring back for dinner. Go ants! Saving seedlings from leaf miner attacks one leaf at a time :)
All that being said, I still think the abstract tunnels in the leaves are very pretty…. Maybe I’m just super bug-biased lol. What do you think? Pretty? Or terrible? You can be my weird-o-meter.
Want to learn more about the Common Aspen Leaf Miner? Check out these resources:
- USDA info sheet
- USDA pamphlet
- Moth Photographer Group (Pictures of the adult moth)
- Scientific article on negative impacts
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The links below are Amazon.com affiliate links. This means that, at zero cost to you, I will earn an affiliate commission if you click through the link and finalize a purchase. This helps pay for my blog and keeps it clean and ad free. I am very selective about what I recommend. The books below are all either on my shelf or ones I regularly borrow from the library…
The last book on the right is the older Peterson moth field guide. I still use it a lot, but all the images are of pinned and spread moths. The newer Peterson moth field guide (first book on the left) has images of moths in their natural poses. Both books are good- it just depends on what your needs are. Are you looking at museum specimens or live specimens?