Ask the Naturalist

Is That Bright Red-Orange Butterfly Supposed To Be in the Bay Area?

November 12, 2015

A couple of days ago (in that stretch of dry autumnal light and weather last week), I saw a good-sized (layperson’s term) orange-red butterfly in my Bernal/Mission/Noe backyard, zipping back and forth for awhile. It caught my eye because I’ve never seen anything that color here, or maybe anywhere out in the world. From what I could see, the description seems to fit a Gulf fritillary … but it wasn’t clear to me that it was reasonable to expect seeing one here and now. What do you think? Thanks. — Nicholas D., San Francisco

Nicholas, it has, indeed, been quite reasonable for a Bay Area resident to see this species since about 1950, when the caterpillar hitched a ride north into our region on its ornamental host plant, passion vine. (We have no Passiflora sp. native to California.)

Though just how they got here has a couple of varying explanations, the answer’s probably close to this: When the love for “All Things Tropical” exploded onto the 1940s Hollywood film scene, into the Southern California nurseries went palm trees, canna & calla lilies, hibiscus and … passion vine! The Mexican butterfly opportunistically pushed its northern extremes as we put this pretty flowering vine into our yards. This gives it the unique status of being our only non-native butterfly on a non-native host.

Another cool factoid: The butterfly’s Latin name, Agraulis vanillae, is based upon an illustration that got it wrong! The butterfly was seen landing on a vanilla orchid, which was then assumed to be its host. The butterfly has nothing to do with the famous, flavorful seed pod, but since Linnaeus’s day, its name has never been corrected.

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Usually late into the fall is when they’re seen bulleting about madly here. Butterflies that host on vines (our other, the pipevine swallowtail, feasts on Dutchman’s pipevine) are remnant jungle creatures that exhibit a frantic, frenetic flight (say that three times fast….).

There isn’t a time I don’t stop as well to marvel at this persimmon-colored beauty. Lucky us.

About the Author

Liam O'Brien is a San Francisco-based lepidopterist. He writes and illustrates the monthly Flying Pansy column for BayNature.org.

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