Antheraea polyphemus Caterpillar

I have eight of these maybe ten, there hard to count, there about 3/4's of an inch long now, will grow to three inches long by 3/4 inches thick by the end of summer. I feed them wild crab apple, tried a few things that were supposed to be host plants but that is what they liked the most, luckly there is one beside the driveway,