Subject: What’s that Caterpillar?
Location: Mariposa area in Sierra Foothills, CA
April 3, 2017 9:09 am
We were romping around our property in the Central Sierra Foothills this past weekend and observed a A LOT of these caterpillars, predominantly on Penstemons, but not exclusively. What are they? Thanks
We quickly identified your Caterpillars as Variable Checkerspot Caterpillars in the subspecies Euphydryas chalcedona–a sierra thanks to this BugGuide image. The Variable Checkerspot is a wide ranging and as its name indicates, variable species, with several subspecies. There seems to be some question on BugGuide if this is a species, or a subspecies, and we would not rule out that it might be a hybrid, but this information is provided: “High elevations in Sierra Nevada of California. Remarks I have difficulty with the idea that this is a subspecies of E. chalcedona and not of E. anicia. It occurs in close proximaty to, and even in the same places as dark, more ‘typical’ E. chalcedona, yet is different. However, all the books and listings I can find place it under this species. The rational for this placement is the structure of the male genitalia. This is an overall orange butterfly that is found in the Sierra Nevada of California and a bit into mountains of adjacent Nevada. A similar situation exists northward in the Cascades, where similarly orange-colored populations are also placed in E. chalcedona (or E. colon) based on details of genitalia. [comment by David J. Ferguson 11-27-08].”