This afternoon I saw an Anise Swallowtail (Papilio zelicaon) coming in for a landing on some Echium candicans flowers growing along the Brooklyn Basin channel between Oakland and Coast Guard Island. These lovely flowers are attractive to butterflies, bees and hummingbirds. Though these butterflies lay their eggs on fennel (Foeniculum vulgare), from which the caterpillars collect essential oils like anethole, which make them taste bad to predators, the adults feed at many different flowers. The caterpillars start out black and white, looking like bird droppings. But as they eat more fennel and accumulate more toxins, they become vividly colored with bright green, yellow and black stripes. Anise Swallowtails breed in spring in areas with serpentine soils — we have many such areas here in Oakland.
Kieran spotted two fat Anise Swallowtail caterpillars on his way home from school in May 2014.
Steven E. F. Brown 