Lepidoptera feathers and hair, bran, semolina and flour (possibly preferring wheat flour), biscuits, casein, and insect specimens in museums. Even though most butterflies and moths affect the economy negatively, some species are a valuable economic resource. The most prominent example is that of the domesticated silkworm moth ("Bombyx mori"), the larvae of which make their cocoons out of silk, which can be spun into cloth. Silk is and has been an important economic resource throughout history. The species "Bombyx mori" has been domesticated to the point where it is completely dependent on mankind for survival. A number of wild moths such
Crustacean larva post-larva is characterised by the use of abdominal appendages (pleopods) for propulsion. The post-larva is usually similar to the adult form, and so many names have been erected for the stage in different groups. William Elford Leach erected the genus "Megalopa" in 1813 for a post-larval crab; a shrimp post-larva is called a "parva"; hermit crab post-larva are called "glaucothoe". In the Branchiopoda, the most basal group of crustaceans, there is no metamorphosis; instead, the animal grows through a series of moults, with each moult adding various numbers of segments to the body, but without any dramatic changes in form.