Las Trampas Regional Wilderness CA
Location: Las Trampas Regional Wilderness San Ramon CA
May 29, 2011 11:10 am
Yesterday afternoon on a lovely hike at Las Trampas Regional Wilderness in San Ramon CA we happened upon a beautiful butterfly perched atop a thistle.
I’ve combed my Laws Field guide and did several searches onilne with no luck. Any guidance you can provide is greatly appreciated!
I took two photos one of the top and I found another on the other side of the trail where I was able to photograph the underside. Thank you!!!
Signature: Cheers! Andie

Variable Checkerspot

Dear Andie,
Your photographs arrived at a very interesting time.  Just yesterday we did a powerpoint slide presentation of Southern California insects at the Theodore Payne Foundation, and there were some gaps in the species represented in our images.  We had no photos of Checkerspots from California, and we believe your photo represents a Variable Checkerspot,
Euphydryas chalcedona.  We used Jeffrey Glassberg’s book, Butterflies Through Binoculars, The West (see Amazon) for the identification, and we strongly recommend it as a choice book for people who want to identify butterflies in western North America.  As the common name implies, there is variability in the coloration and markings.  Most individuals have three bright orange patches on the leading surface of the forewings, which your individual lacks.  There is a matching photo in Glassberg’s book that is listed as being from San Mateo County.  Your sighting was in nearby Contra Costa County.  In your individual and in the one illustrated in the book, the bright orange patches are black.  This is undoubtedly a regional variation.  Since this information is not available online to our knowledge, we are going to quote liberally from Glassberg’s book:  “Extremely variable.  Varies from primarily red-orange above, to primarily black, to very white and everything in between.  … Many, but ot all, populations of Variable Checkerspots have at least some white spots on the abdomen, set off-center.  … Many, but not all populations of Variable Checkerspots have luminous yellow antennal cluts, with little if any black at their base.  … Habitat:  Many open situations, including mountain meadows, desert canyons and high elevation barrens.  Abundance:  C-A.  March-May in southern California.  , southeastern Arizona – southwestern New Mexico (hermosa);  mainly May-July elsewhere.  Food:  Beardtongues, Indian Paintbrushes, snowberries (colon) , and others.”  You may view BugGuide for additional images of the Variable Checkerspot.  Thank you for supplying our archive with your excellent images of an underrepresented species.

Variable Checkerspot

Hi Daniel,
Thank you so much for your quick reply and for the information provided as well as the BugGuide website (which is now bookmarked). I’m super excited to have managed a photograph of such an underrepresented species! What luck! My husband is the one with the phenomenal sighting and I am ever grateful to my recent mother’s day present “Big Betty” and her amazing zoom lens!
I’m so happy to supply your archive! I clicked the link for your FB page as well so I’ll be happy to post there too. Yay nature!!!
All the best,

Dear Andie,
Your enthusiasm is positively infectious.


Location: California

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