Sandy found this medium-sized black moth in the house on June 2, 2012. It had probably been attracted to the house lights at some point, and then snuck inside when somebody opened the door.
It looked really, really black while it was fluttering around the house. It actually looked a lot like those big, sooty ashes that you see rise up in the air when burning cardboard boxes. But, when we caught it in a transparent plastic container and looked at the underside, it was actually quite pale on the bottom.
While a lot of moths look broadly similar, the particular way it holds its wings and the pattern of lichen-mimicking stripes, along with the pale spots on each wing, sure look to me like a Black Zale, Zale undularis.
BugGuide says the caterpillars eat black locust and honey locust, so it probably came from the patch of black locust growing on the southeast corner of our property. Judging from the range map at the Moth Photographers’ Group, we are at pretty much the extreme north-western extent for this moth, so it may be unusual for us to see it. The places that report the most sightings look pretty much identical to the original native range of the black locust,, so it’s probably just a matter of time before this moth follows the spread of the locust trees all over North America.
 Incidentally, around here black locust is either a pretty good living fence, or a pretty nasty invasive plant, depending on where your priorities lie. I understand that in its native range it becomes quite a large tree, but in most places the locust borers kill the shoots before they get more than a couple of inches across, and the plant then “suckers” up from the roots to form a dense thicket. While it is a North American plant, its original native range was restricted to the Appalachians, and outside that range it behaves a lot like invasive plants from other continents. It’s a legume, which means it fixes its own nitrogen from the air rather than requiring nitrogen fertilizers, and it can therefore grow in poor soil. The particular variety that we have comes up from underground runners, which in our yard sometimes run twenty or thirty feet from the main patch of trees before they send up a shoot. We know they are from runners and not seeds, because on a couple of occasions we’ve pulled up a little locust sapling way out in the middle of the yard, and then continued pulling up the runner all the way back to the main patch. The patch of black locust itself is pretty nearly impenetrable, because the trees are not only close together, but they have some pretty nasty thorns on them.
Oh, and the seeds are poisonous (although they are supposedly edible if cooked thoroughly). The bees like the flowers, though, so at least there’s that.