Paul and Steve found this little guy on a wood post on our outing to Mitchell Canyon on Mt. Diablo -near Clayton, California.
Paul was sweet and let me shoot him. He is about 1 1/4" or 3mm.
I believe he is a caterpillar of the Rusty Tussock Moth (Orgyia Antiqua) - common on willow, white oak and black cottonwood
in Pacific Northwest. I may be wrong on the ID - closest I found in online source.
1/25s f/4.6 at 72mm iso-50 with 5T CloseUp Lens and tripod