Overnight, the majority of the caterpillars changed their skins. They spin a pad of silk, and then hook their rear feet in the silk; then they wiggle and shimmy their way out of the old skin. This is an old skin. You can see the rear feet at the top left, and you can see some of the hairs from the old skin in the middle of the shot. Click on the picture for the bigger version.
Here, you can see a first-instar caterpillar (left) who’s a day or so behind the game. The difference in size between the first instar and second instar head casings is substantial.
When they come out of the day of rest with new skins, they have a voracious appetite; they turn the mulberry leaves into lace.
It’s hard to get the focus just right to see it, but the head casings are surprisingly hairy.