As you've already guessed, probably has to be either Limenitis arthemis arthemis, L. astyanax astyanax or L. archippus archippus in the New England states, or a hybrid of them. For those especially interested in this group... Some authors use Basilarchia instead of Limenitis FWIW (the genus name used for this group on other continents). It gets real confusing identifying the larvae of this genus out west where we have at least L. arthemis rubrofaciata, L. astyanax arizonensis, three subspecies of L. archippus, 5 subspecies of L. weidemeyeri and 2 subspecies of L. lorquini. I was very fortunate to do rearing work for years with Austin Platt (Professor of Biological Sciences at UMBC) on the population biology and genetics of this group in North America. All species can be made to intergrade in lab controlled mating, with the resulting characteristic ratios of those crosses now pretty much known. So they could also hybridize in nature as well where ranges overlap. Some crosses are extremely rare in nature though, even in blend zones. I have a great series on this group and its hybrids in my synoptic collection from my work with Austin, including an example of the rarest of the rare hybrids - an interspecific hybrid form rubidus dark morph that came from a female L. a. archippus X male L. a. astyanax in 1983. At the time it was one of only about a half dozen known. If you really want to know more about the intra and inter specifics of this group (complete with color plates showing the relationships), Austin has published it. My copy is buried somewhere in storage and I can't remember the year or title - sorry.

Wiki says it takes about 2 weeks to eclose but could go into diapause. http://www.sierrapotomac.org/W_Needham/LunaMoth_050911.htm Clemson Univ. has some useful information with notes on northern food preferences. http://entweb.clemson.edu/eiis/pdfs/bb7.pdf From what I read diapause/overwintering is dependent on number of factors. They overwinter by falling off leaf where cocoon was made into leaf litter and emerge in spring to mate. You may have a winter guest after all. "The luna moth pupates after spinning a cocoon. The cocoon is thin and single layered. Shortly before pupation, the final, fifth instar caterpillar will engage in a "gut dump" where any excess water and fluids are expelled. The caterpillar will also have an underlying golden reddish brown color and become somewhat immobile. As pupa, this species is particularly active. When disturbed, the moth will wiggle loudly. Pupation takes approximately two weeks unless the individual is diapausing. The mechanisms for diapause are generally a mixture of genetic triggers, duration of sunlight or direct light during the day, and temperature." Canadian Wildlife Federation information linked below is good. Good luck...what a find! Here is a link that might be useful: Canadian Wildlife Federation - Luna Moth

White-marked Tussock Moth is my guess. My immediate thought was that it was some sort of a Tussock Moth cat. I did some research, and it looks just like the White-marked Tussock Moth caterpillar to me. Gorgeous shot BTW, and lucky you!! :o)

If they are fuzzy, they may be tussock moth. A pest on sycamore trees, but am not too familiar with them and there must be many species. The hairs cause skin irritation.