Promethea – second instar
The Promethea caterpillars are changing to second instar. They’re seven days old.
They have not all shifted yet – they may have hatched across two days, or some may just be a little delayed. You can see that the remaining first-instar caterpillars are smaller, and also yellower than their second-instar siblings.
You can see – especially on the stripe behind the head – that they’re beginning to develop a white, flaky cortex – as they get older, it will develop almost into a crust. I don’t know whether this helps to make them unpalatable to birds, or what.
I like the picture of the first and second instars together. If I had endless time, I would design a textile with black and white stripes and supplementary yellow wefts (perhaps warps also) sheared away to form little bundles decorating the white stripes. How many instars before they begin to spin?
Carla