Silk production. Textile worker with several silk moth (Bombyx mori) cocoons in water having their silk threads harvested. These are used in the manufacture of silk. The silk cocoons are produced by the silkworms (caterpillars) before they pupate to protect the pupae during metamorphosis. The pupae are killed to prevent the emerging moths damaging the silk. Each cocoon is made up of over 250 metres of fine silk thread. The threads from several cocoons are woven together by the machine at upper right to make the silk thread used in textiles. Photographed in France.