Geographic location of the bug: Siskiyou county, CA
Time: 02:05 PM EDT
Your letter to the bugman: I found this little guy crawling through the Oak Leaves in my yard. I’ve never seen one like it.
How you want your letter signed: Donna B
If our identification is correct, we believe this is a Mendocino Saturnia Moth Caterpillar, Saturnia mendocino, a caterpillar not well represented on the internet. We located a similar image that we cannot link to, and then we located this image on iNaturalist that looks remarkably like your individual. According to Pacific Northwest Moths: “The last instar larva is yellow and has scoli or tubercles covered with orange hair tufts and longer white hairs. It is illustrated by Miller & Hammond (2003). Miller & Hammond (2007) also illustrate the young larvae that change dramatically in color pattern with each instar.” According to Butterflies and Moths of North America: “Caterpillar Hosts: Manzanita (Arctostaphylos) and madrone (Arbutus menziesii), both in the heath family (Ericaceae).” Do you have those host plants growing nearby? We will check with Saturniidae expert Bill Oehlke to verify this identity. He may request permission to post your image to his site.