Small caterpillar of a California Sister butterfly
This is a small caterpillar of a California Sister (Adelpha bredowii) butterfly on a half-eaten leaf of Coast Live Oak (Quercus agrifolia, Fagaceae). That looks like a nest down below it, composed mostly of frass (poop). This one is less than 1/2 inch long, but they look remarkable when they are larger - see this photo and this photo. I found two other small caterpillars last winter, see my photos here and here, but I lost sight of them over winter. I'll try to keep in contact with this one as it matures, it's on a small enough tree that I should be able to find it again. (San Marcos Pass, 1 June 2020)
Small caterpillar of a California Sister butterfly
This is a small caterpillar of a California Sister (Adelpha bredowii) butterfly on a half-eaten leaf of Coast Live Oak (Quercus agrifolia, Fagaceae). That looks like a nest down below it, composed mostly of frass (poop). This one is less than 1/2 inch long, but they look remarkable when they are larger - see this photo and this photo. I found two other small caterpillars last winter, see my photos here and here, but I lost sight of them over winter. I'll try to keep in contact with this one as it matures, it's on a small enough tree that I should be able to find it again. (San Marcos Pass, 1 June 2020)