Comma, Question Mark?
No, the title isn’t just me listing punctuation marks for no reason. Those are the two possible common names I’m trying to decide between for this butterfly:
Sam netted it from our lilac bush on May 20, 2012. It’s in pretty rough shape, because this is one of the species that overwinters as an adult, and it has been an adult for 6-8 months (which is positively ancient for a butterfly). It’s definitely one of the anglewings in the genus Polygonia. Even though a lot of the wing edges have been broken off, and the colors are kind of faded, the pattern and wing shape is very distinctive.
Getting it down to species, though, is harder. There is supposedly a distinguishing mark on the underside of the wings.
See that white mark on the wings? If it looks like a comma, then the butterfly is a Comma, but if it looks like a question mark, then it is a Question Mark. Problem is, I don’t think this looks like either a comma or a question mark. If I rotate it so that it actually looks like a puctuation mark, I think it looks most like a semicolon, if anything.
The Question Mark, Polygonia interrogationis, has the two white marks, but the smaller mark is more aligned with the middle of the larger mark than in this specimen. The rest of the Polygonia genus (the Commas) all have a single white mark, but the one that looks the most like this specimen (the Eastern Comma, Polygonia comma) would have the right shape of the white mark if the neck was a bit narrower to make it two marks instead of just one.
You know what? I’m just going to call this one the Northern Semicolon and be done with it.
Anyway, here’s a picture of its head:
In either case, the larvae eat nettles, and hops, and elm, and have two generations. The summer generation has lighter-colored hindwings, and the generation that emerges as adults in the fall has dark hindwings (probably to help them more readily blend in with dead leaves and lichen while they hibernate over the winter). The adults only rarely come to flowers (although this one was caught on lilac blossoms). They mostly prefer juices from rotting fruit, sap, and fluids from damp soil (which may contain some salts that they like)