Whilst working in woods near Flimwell, on the East Sussex and Kent border earlier in the week, I came across an empty cocoon on the trunk of a birch tree. Kitten Moths make very similar cocoons in which to pupate but the large size of this cocoon (40mm long) suggested Puss Moth (Cerura vinula).
It is a wonderful structure made from larval silk mixed with chewed up tree bark. It sets to a hard shell and is perfectly camouflaged to protect the over-wintering pupa.
They are also very hard to find and if it wasn't for the exit hole catching my eye then I may well not have seen it. The occupant of this cocoon probably hatched last summer but I suspect that these empty cocoons can last for years.
The adult Puss Moth (Cerura vinula) is a stunning creature and a species that comes to my garden light-trap most years.