{"id":279,"date":"2026-05-22T23:33:25","date_gmt":"2026-05-22T23:33:25","guid":{"rendered":"https:\/\/sanfranciscomovingguide.com\/?p=279"},"modified":"2026-05-22T23:33:25","modified_gmt":"2026-05-22T23:33:25","slug":"massive-butterfly-swarm-becomes-the-talk-of-santa-cruz","status":"publish","type":"post","link":"https:\/\/sanfranciscomovingguide.com\/?p=279","title":{"rendered":"Massive butterfly swarm becomes the talk of Santa Cruz"},"content":{"rendered":"
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Exceptional. Magical. Healing. Santa Cruz area residents seemingly cannot stop posting positive adjectives about the unexpected wave of butterflies flooding their region.<\/p>

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On Mother\u2019s Day, the thick blanket of orange and brown butterflies arrived in Shannon\u00a0Robbins\u2019\u00a0garden in Bonny Doon, a community in the Santa Cruz mountains devastated by the CZU Lightning Complex fires in 2020.<\/p><\/div>

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The winged insects have not left yet, though their numbers seem to ebb and flow.\u00a0<\/p><\/div>

\u201cIt\u2019s very uplifting,\u201d Robbins, a landscape designer who has lived in Bonny Doon for two decades, told SFGATE. \u201cEveryone here is so excited.\u201d<\/p><\/div>

The butterflies resemble monarchs, a species on brink of extinction that shelters along California\u2019s coast every winter. Yet the visitors are in fact a more prosperous insect called California tortoiseshells (Nymphalis californica), whose sudden appearance in Santa Cruz came as a surprise to local ecologists, too.<\/p><\/div>

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\u201cThe irruption of California tortoiseshell butterflies in Santa Cruz County is episodic and very unusual in my experience from 1986 to present,\u201d Grey Hayes, an ecologist who lives just north of Santa Cruz, wrote to SFGATE.\u00a0<\/p><\/div>

Although residents have not seen swarms of tortoiseshells in Santa Cruz for years, spring always marks a seasonal migration for the species from lower to higher elevations. They time their travels with the budding of wild lilacs, where they lay their eggs. Tortoiseshell populations, found throughout the West, are known to explode some years when the conditions are just right.<\/p><\/div>

\u201cThis is a mass migrant that makes news at irregular intervals by tying up traffic!\u201d Arthur Shapiro, an emeritus professor at UC Davis who specializes in butterflies, wrote about tortoiseshells. He added: \u201cAdults emerge in late May to early June and almost immediately emigrate, going north or east and upslope. Breeding localities in summer vary widely from year to year – sometimes in the high southern Sierra, sometimes in the Cascades… sometimes only in far northeastern California or even farther north.\u201d<\/p>

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Shapiro wrote to SFGATE on Thursday evening: \u201cI just got a report of lots of torties at Hastings Reservation (Carmel Valley) today. That and the Santa Cruz reports suggest the source is the central Coast Ranges south of the bay.\u201d<\/p><\/div>

Another exceptional swarm cropped up in 2019 to the delight of Lake Tahoe\u00a0residents.<\/p><\/div>

Hayes told SFGATE that the last time he noticed tortoiseshells in Santa Cruz County was in 2017, which was eight years after the Lockheed Fire.<\/p><\/div>

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