Picture cocoon 014

Picture cocoon 014

Observation - Picture cocoon 014 - UK and Ireland. Description: One of several found in garden. All others are open and empty. Found at base of leylandii in leaves and twigs. Kidney shaped and parchment like. 8 cms long by 5 cms wide. pupa 5 cms long by 3 cms wide. What is it?

One of several found in garden. All others are open and empty. Found at base of leylandii in leaves and twigs. Kidney shaped and parchment like. 8 cms long by 5 cms wide. pupa 5 cms long by 3 cms wide.

What is it?