Two cocoons in process of being spun by larvae (caterpillars) of the Saturnid moth,Samia cynthia. The cocoons are anchored to twigs of golden privet,Ligustrum vulgare,and each will eventually contain a pupa. In the picture,the larvae are just discernible beneath the silk covering. Each cocoon is approximately 5cm long. Silk is produced from two components,fibroin and sericin. The diameter of each strand is approximately 15microns,and each final cocoon will contain several hundred metres of silk. S. cynthia is one source of "wild silk". Commercially produced silk is made by a different moth,Bombyx mori,an entirely domesticated species unknown in the wild. S. cynthia is native to Central and Eastern China,but is now also found in parts of Europe and the USA following importation |