This has been the week for submissions of caterpillars of the giant swallowtail. The larva is very distinctive in appearance and feeds on leaves of trees in the citrus group. Of course they can grow quite large and consume many leaves in the process of developing. The question posed by people, when they find out these are swallowtail larvae, is whether they can move the larvae to some other type of tree so as to halt the damage to their citrus (usually lemon or lime trees). In short the answer is no, because this species can only feed on citrus. Other hosts in addition to lime and lemon are common pricklyash and common hoptree. The adult insect is a stunning butterfly and here is a link to more information on Bugguide.