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Object of the Week: California Tortoiseshell Butterfly

Ryder Diaz, Curator of Natural Sciences, reflects on the many stories behind a jar of butterfly pupae in OMCA’s collection.


Every week, OMCA staff—from curators to gallery guides—reflect on an object from the Museum’s extensive collections that shares insights and inspiration for our present moment. 

From Ryder Diaz, Curator of Natural Sciences

I’ve been spending a lot of time in my garden appreciating the Bay Area’s beautiful butterflies as well as thinking about transformation and change. Today I want to share with you this jar of butterfly pupae that’s in our collection because this one jar holds many stories.

These pupae are likely those of the California tortoiseshell butterfly, which can be seen along the coast range from fall through spring. All butterflies undergo incredible changes. A caterpillar emerges from its egg to feast on plants and once it has grown large enough, it enters its pupal stage. As a pupa, it transforms from a wingless animal to a winged butterfly. Butterflies generally don’t make cocoons; they pupate as a chrysalis, protected by a hardened exterior.

In California’s foothills and along the coast range, adult California tortoiseshell butterflies emerge from chrysalises in May and early June. They then migrate to higher elevations in the Sierras or up north. While scarce some years, other years this species’ population size explodes. Tortoiseshells have been seen migrating in swarms 50 miles long by 15 miles wide.

Charles Wilcomb, the founding curator of the Oakland Public Museum, collected these pupae in 1911 from indigenous Californians–the Maidu–in Butte County. Though Wilcomb usually paid indigenous communities for items, we know that these were not fair or just exchanges. It’s important to recognize that there are many objects in museum collections that were taken without consent, compensation, and by force. Today, OMCA and other museums are working to change that legacy through the return and repatriation of cultural objects and honest collaboration with communities.

A note that accompanies this jar of pupae reads “toasted for food purposes.” I was excited to learn that these pupae have been eaten by the Maidu and several other California indigenous tribes. We know that insects have always been part of human diets and that insects are extremely high in protein. Currently, insects supplement the diets of approximately 2 billion people and they do so with far less environmental impact than cattle. As someone who enjoys chapulines—those are edible grasshoppers eaten mainly in Mexico—I am very curious what a fresh batch of these butterfly pupa might taste like.

What caterpillars and butterflies are you seeing in your neighborhood right now and what stories might they hold?