Dead

That sad looking caterpillar is a dead pipevine swallowtail. I don't know why it died, but I suspect that the Aristolochia manchuriensis that it was feeding on is just too toxic. The butterflies seem to prefer to lay eggs on it, and the caterpillars become so dense on the leaves that they sometimes completely defoliate the vine. But they don't seem to survive very well. Even some of the larvae that I brought inside and fed on Aristolochia californica died. But those that I collected from A. californica and raised on A californica did fine. So I wonder what is going on here. Maybe I will do a study next year.