Looks like you found yourself a Luna Moth caterpillar. Congrats! Judging from its amber color, it's ready to make its cocoon, so if you'd like to keep it, put it in a container with some leaves and leave the rest up to mother nature!

I just brought in some Alder and wild Pussy Willow branches with leaves on them since someone told me that's what it probably was, but I surely appreciate the ID from you. :O) I placed a few on the bottom and he is definitely wanting to make his cocoon since some webbing is coming from him.

Do I overwinter this baby? How?

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

Congrats on your pupating luna cat! I'm raising some little bitty ones myself.
Sherry

Thanks everyone. I've called it 'Big Daddy'!! :O) Just had to name this one.

I had to take over one aquarium from the Monarchs for this baby. I have leaves and branches of Willows, Alders, and White Birch in there but so far BD hasn't eaten. Just meandering around lazy like and checking things out and getting more orange as the day ends.

We'll see what tomorrow brings. Thanks again!