This was Willow yesterday:
She has outgrown her seat leaf:
The next two pictures show Faith, today:
Allowing 17-18 days for the 5th instar and two or three for pupation, both these caterpillars should pupate in May.
At the other extreme, I found a freshly moulted 3rd grader, Xander, the other day. He must have spent the winter as a second grader - something that happens relatively frequently here:
Most of my other cats are currently in 4th grade.