Pipevine Swallowtail Caterpillar

I did a little research on the creature I met on my San Bruno Mountain fog walk. It turned out to be a Pipevine Swallowtail caterpillar, the larva of the butterfly of the same name. Apparently the butterflies only lay their eggs on the pipevine, and the larva eat the leaves, which contain a toxin so the caterpillars are poisonous to birds and don't get eaten. The individual I met did seem remarkably focused on his or her journey. Perhaps he or she was looking for a place to pupate. The above photo of another Pipevine Swallowtail caterpillar is from larvalbug eye, a free nature image source.

The California pipevine, Aristolochia californica, is native to San Francisco and the Bay Area. It has an odd-shaped flower, supposedly like a pipe. Maybe I'm a square, but I've never seen anyone smoke a pipe that looked like that. Now I have a mission: next time I go up to San Bruno Mountain, I'm looking for the California pipevine, and maybe I'll see one of those beautiful butterflies.

There are some gorgeous photos by Paul Furman, on baynatives.com, of Pipevine Swallowtail butterflies mating on San Bruno Mountain and of the weird flowering Aristolochia californica. I really really wanted to put his photos on my site (with a credit, of course), but I just couldn't do it. I've been struggling with the question of when I can use other people's photography on my blog, but in this case it just didn't seem right. So you'll have to visit over there to check the photos out.

P.S. August 25, 2007: I saw a Pipevine Swallowtail butterfly on San Bruno Mountain today! It was feeding on agapanthus, and shimmering blue when it turned my way.