Inch Worm?

Nearly short sleeve weather this evening when I was actually pulling weeds in a flower bed. That in and of itself is rather interesting since a week ago there was still snow on the ground. And now who is this little green guy?
After taking its portrait I set the leaf and worm.caterpillar outside.
I hope it is a white butterfly but... any ideas? Amazing that it hatched out in such weather. It was below 32ºF last night.
Nature is so wonderful.