Dun-bar Moth Caterpillar Cosmia trapezina

Dun-bar moth caterpillar on willow.

Another of the many green caterpillars for camouflage amongst leaves which becomes a brown moth for adult camouflage.

Wasn't sure whether the caterpillar was spinning silk to pupate or just to protect itself while feeding. Given its large size and the way it has attached silk strands to the stem as well as the sheath, it is probably pupating and ensuring the pupa is covered when the leaves fall in autumn.