Pacific Tussock Moth
I’m just one of those people who work at the Exploratorium who loves your site, so I thought you might like to see an invader that concerned me earlier this year. The caterpillar in question was eating all the ground cover over a large area on the side of the hill where I live on Mount San Bruno, just south of San Francisco. Here’s what it looked like on the human-scale: Note the brown eaten area. Not a leaf left! I consulted a local expert and he informed me that the culprit was the Pacific Tussock Moth, Hemerocampa vetusta, which I couldn’t find in your collection of caterpillars, so here you go – a small portion of the MILLIONS that were out there: And a close-up: Keep up the good work!
Thank you for the nice letter. As you stated, this is a new species for us. We always like to research new species. We did locate a caterpillar on BugGuide that looks identical to yours that is identified as the Western Tussock Moth Caterpillar, Orgyia vetusta. The genus formerly known as Hemerocampa is now recognized as Orgyia. Thank you for the images.