The larva was found mid-day. I originally identified it as genus Manduca, but their host plants are members of the Nightshade family. This specimen was feeding on Ceanothus prostratus. You will notice the anal "horn" is almost a light violet in color, which made me suspect Manduca quinquemaculata at first. However, the chevrons on the sides of the specimen are all wrong for the that species. It's probably something else entirely.