I think I figured it out?
Location: Sonoma Mountan Range, California
December 15, 2010 2:09 am
Hi there, this is a photo I’ve sent before but didn’t hear back about…(no worries). I’ve continued to research and now I’m pretty sure it is the ceanothus silk moth larvae. I see you don’t already have a picture posted of the larvae, so I thought maybe you’d like to have it.
First we apologize for not responding to your earlier email, but it may have arrived on a busy day and gotten overlooked. This is not a Ceanothus Silkmoth Caterpillar. This is a Royal Moth Caterpillar in the subfamily Ceratocampinae, and though there are some inconsistencies in the colors and markings, we believe it is the caterpillar of Hubbard’s Small Silkmoth as that is the only member in the subfamily known to be found in California. You can compare your image to the images on BugGuide an you will see the resemblance, but also the inconsistencies. Since Hubbard’s Small Silkmoth is supposedly limited to the Eastern portion of the state and not near Sonoma, we have our doubts. We are going to check with Bill Oehlke to get his opinion on this puzzling mystery. Dare we entertain the possibility that this is an unrecognized species? Do you have any additional photos of this caterpillar?
Bill Oehlke responds with a correction
It is Hyalophora euryalus. The shrivelled body makes the scoli seems exceptionally long.
I think it is probably fourth instar.
Ed. Note: Bill Oehlke’s response supports Mollyanne’s original identification. This is indeed a Ceanothus Silkmoth Caterpillar, Hyalophora euryalus.