Two weeks ago I was walking across the Amherst (Massachusetts) town common and I had two minutes to kill before a bus arrived, so I stopped under a Norway maple tree to see if I could find any mines of Ectoedemia sericopeza (Nepticulidae), the “Norway maple seedminer,” in any of the fallen samaras (“keys”) lying beneath it. It had been a long time since I’d seen a photo of one of these mines, so I didn’t really know what I was looking for–I imagined them looking something like the mines other nepticulid moths make in leaves (e.g. these), only in a key rather than a leaf. I saw nothing of the sort, but each key I examined had a little brown line like this:
Closer inspection revealed that each one began with a flat eggshell (as shown in the next photo, a zoomed-in version of the first one), then disappeared into the seed.
Doing some quick investigation when I got home, to see if I had in fact found what I was after, I saw the statement here that “infested samaras are prematurely shed, and should be sought on the ground.” This explained why literally every key I had picked up had had one of the mines in it. I stuffed them all in an empty hummus container and forgot about them until yesterday, when I peeked in and discovered three surprisingly large moths (3.5 mm long, twice the size of the leaf-mining nepticulids I’m used to raising).
I like this moth’s fuzzy orange head and white “earmuffs,” and I also like seeing invasive nonnative plants colonized by host-specific nonnative insects. Incidentally, this moth has a native relative, Ectoedemia ochrefasciella, which has been associated with sugar maple. Its immature stages are unknown, but it is strongly suspected that the larvae mine keys in the same way. So when you see the first sugar maple keys falling, it’s worth taking a look for similar brown lines leading into their seeds.