No one commented on the latest identification challenge. Despite showing just the tip of the forewing, the image provided showed the distinctive feature of a subfamily of moths commonly called hooktip moths. If you got that far, it’s a pretty simple process of elimination since there are only a handful of North American species, each one easily distinguished from the other. This species is the Arched Hooktip, Drepana arcuata.
This individual appears to be a male, based on the widely bipectinate antennae.
As I mentioned in the original post, this moth was reared from a caterpillar I encountered late last year. They feed on alders and birches. I found this one on alder, within a leaf it had folder over using its own silk.
I raked my fingertip through the silk, in order to get a clearer view.
These caterpillars have enlarged warts, shown here.
It’s actually quite a handsome caterpillar. Note the bands on the head capsule, which no doubt inspired its common name, Masked Birch Caterpillar.
One other interesting thing about these caterpillars is that they scrape or beat parts of their anatomy against the leaf in order to advertise their presence to neighboring individuals. In this way they can space themselves out and avoid unnecessary competition.
by David L. Wagner