Euphydryas editha augustina

Edith's Checkerspot

I know this butterfly from the Big Bear area, and it was named based on the San Bernardino Mountains populations, but it probably ranges into the southern parts of the Sierra Nevada according to Ken Davenport. This checkerspot can be common on certain hikes in May-June around Big Bear Lake as the single brood begins establishing another generation. The silk webs of larval nests begin appearing in June-July as the tiny caterpillars hatch and form protective shelters in their food plants, mainly species of paintbrush. Two plants I've personally seen caterpillars eating are Castilleja applegatei (the favorite) and Pedicularis semibarbata (not often used). There may be another species of paintbrush along Siberia Creek Trail that they use, but I haven't been able to identify it yet. The caterpillars overwinter as mid-instars at the base of the plants, and will begin feeding again as soon as the snow melts and the plants begin to sprout from the wet ground. They can have more than five instars as they feed, and can take shelter again and become quiescent if necessary. Finally they pupate and the big flight soon begins. Female adults deposit bunches of eggs on the plant leaves, and the race is on: they need to get to the third or fourth instar and they must enter diapause.

Euphydryas editha augustina - 'August' Edith's Checkerspot
This is Euphydryas editha augustina from the Bluff Lake meadow area near Big Bear, June 17th, 2012.
Euphydryas editha augustina - 'August' Edith's Checkerspot
These Euphydryas editha augustina can be locally common around Big Bear. These were along the PCT east of Van Dusen Road, Big Bear, May 6, 2006.
Euphydryas editha augustina - 'August' Edith's Checkerspot
Another Edith's checkerspot from the same hike.
Euphydryas editha augustina - 'August' Edith's Checkerspot
Ventral of Euphydryas editha augustina, same hike. The endangered Quino checkerspot is a different subspecies of editha, thus a close relative.
Larval nest of Euphydryas editha augustina - 'August' Edith's Checkerspot larva
Later in summer, after the flight, one can find these larval nests if you look for them in their habitat. August 5, 2023 on Siberia Creek Trail.
Caterpillar of Euphydryas editha augustina - 'August' Edith's Checkerspot larva
This is a post-diapause larva of Euphydryas editha augustina. I found several feeding and taking shelter at the base of Castilleja applegatei at the trailhead of the Sugarloaf Trail in Big Bear. This photo is from April 24, 2022.
Original description of Euphydryas editha augustina - 'August' Edith's Checkerspot larva
William G. Wright explored the San Bernardinos in the 1890s and early 1900s and he is credited with naming this butterfly in his 1905 book The Butterflies of the West Coast. There is some confusion over the names augusta and augustina, but it seems augusta is what we now call quino, so augustina applies to the higher elevation San Bernardino Mountain populations.

©Dennis Walker