What is this German caterpillar?

[catman7]

Hi

I am glad to have found this great website.
Do you know what this German caterpillar is?
It was found on a beech tree. I suspect it is some kind of moth.

http://commons.wikimedia.org/wiki/File: ... 05-19.webm

Many thanks

Catman

[Essex Bertie]

I've checked the modest list of UK beech-feeders in Manley's book without success. So one of the many hundreds of Geometer moths is the best I can do, sorry.