Posing near the Herb Dengler Trail, Jasper Ridge. 6/29/2021, 11:34:56 am. It looks a lot like the California Sister (Adelpha californica), which is inedible. A mimic. And Art Shapiro thinks the larva might mimic a bird dropping... Native throughout the West, to Montana. Wikipedia: "They are extremely territorial and will attack any intruders into their habitat, including large birds." Do you believe that? Thanks to Bob Dodge for the ID!