Leaf Miners

If anyone can tell me what critter made these I would appreciate it! The trail is light pink with a shimmer to it :)

I found this suspicious trail on a hike this past weekend. It looks like someone took one of those glittery gel markers and drew all over a leaf! My botanically-inclined companion informed me this is the work of a leaf miner. The term loosely refers to the larvae of any insect that lives within the leaf and eats the cellulose material. That way, the little critters are somewhat protected from predators and any chemical plant defenses that may exist on the outer layers. Pretty sneaky of them...

The Wikipedia page cited a 2009 BBC article mentioning the discovery of a plant from Ecuador that has suspicious leaf miner markings... but not caused by an insect at all! One of the first things we learn in biology class is that chlorophyll allows plants to make energy from the sun and gives them their green color, right? So, if a plant has splotches of white on the leaves, that just decreases the area on which photosynthesis can occur...non bueno right? Not so! These researchers from Germany found those splotches might be doing good in another sense...

Traipsing around the Ecuadorian forest they noticed a plant that sometimes had fully green leaves and sometimes had leaves with white splotches:

"A leaf damaged by mining moths (left) compared to one faking it (right)."

They also noticed that the fully green leaves seemed to be infected by leaf miners more often than the splotchy one. A hypothesis was born. They hypothesized that plants 'faking' leaf miner infestations would have less damage from actual leaf miners (in this case it was a type of moth) because insects prefer to lay their larvae in uninfected leaves (duh, more food and no damage). They did some experiments with green leaves, splotchy leaves, and hand-painted splotchy leaves (they used white-out!) and found that moths indeed preferred to infect fully green leaves. (By the way, they did tests to see if the chemicals in the white-out affected moth behavior and it didn't.)

This is the official scientific paper but if you just want a cursory look the BBC article does a good job casually pinning down the main points. So, that's how a quick internet search on the pretty pink  leaf trail ended up being a blog post! Pretty cool huh? If enough of these plants start faking it I wonder if the moths will wise up and start using more non-visual cues to assess infection...


Soltau, Ulf, Stefan Dötterl, and Sigrid Liede-Schumann. "Leaf variegation in Caladium steudneriifolium (Araceae): a case of mimicry?." Evolutionary Ecology23.4 (2009): 503-512.