...and he'll take a mile

Charlie:
I dare say your ID is spot on as I was out today with my friend David and we also found a couple of these as shown in David's webpage. Did yours have blue spots and a blue line along the side? I like it how you caught it in motion.

I've been watching an AMC series called 'The Walking Dead' this past week, this B&W shots subdued 'atmosphere' brought it to mind.
They walk very slowly ya know, an 'inch' at a time..And you certainly don't want to run into a 'walker' at night

Hi Charlie. I like the subdued mood here, with muted colors (or B&W conversion) and suppression of highlights. Combined with the low point-of-view, it makes me feel like I am hiding, and hoping the looper does not see me in the dim light -- either because I am hunting it, or perhaps trying to escape detection.

RE: ID -- I'd do the same thing -- just stop at family Geometridae, since there are so many look-alikes. (and larval ID is a pain anyway, and I am certainly not an expert in that field.)

Most (but not all) "loopers" (caterpillars who walk like that) are Geometrids; If there are only two pairs of those soft "prolegs" -- both at the end of the body -- it's a Geometrid. (Also, a few Geometrids, and a few larvae from other families have three pairs.)

By the way, I see you mentioned "6 subclasses" of North American Geometrids. Since I listed a rough hierarchy of the scientific classification system in a comment on your last macro post, I should probably note that your source for info on this family used the term "subclass" kind of generically. In that sense, "subclass" is not a subdivision of the term "Class", which is a huge classification level such as "Class Insecta" for all insects, or "Class Arachnida" for all spiders. The "6 subclasses" they talked about are really subfamilies. They probably did not call them subfamilies because they did not want to have to explain arguments that insect taxonomists always seem to be having about lumping or splitting groups into "subfamilies" (subgroups of family) versus "tribes" (lumps of related genera within a family or even a subfamily). Seems kind of silly, but taxonomists are increasingly trying to make classification meaningful in terms of genetics and evolution.