Spotted in Hawkwell, Roger Payne (Essex Field Club), says this is a Puss Moth caterpillar in its final stage, before it spins a cocoon and then pupates. They change to this colour which is quite different from their normal colouring and find a branch or twig to fasten on to. They chew bits of wood off the branch and mix it with silk to make a cocoon which totally covers them, then they pupate. This reinforced silk cocoon then hardens and the pupa remain inside until next spring when the beautiful moth emerges.
