Silk moth larvae eat mulberry leaves and spin large amount of silk before pupation, which is the important raw material for spinning and weaving. It is also called “Home Silkworm”, silkworm in short, and is one of the economic insects which are mainly fed by mulberry leaves, spin silk and make cocoons. It belongs to Lepidoptera Bombycidae and its scientific name is Bombyx mori Linnaeus. Originated in China, silkworms are domesticated from primitive silkworms resting on mulberry trees in the ancient times. With 28 pairs of chromosomes, they have the same origin of wild silkworms which eat and damage mulberry trees today in China.
The growing temperature for silkworms is 7-40 C while the suitable rearing temperature is 20-30 C. The main regions include temperate, subtropical and tropical zones. Silkworm is an insect with complete metamorphosis. Its entire life includes four completely different growing stages in shapes and physiological functions, which are ovum, larva, cocoon and adult insect. Ovum is the stage to develop embryo and grow into larva. Larva is the growing stage to absorb food nutrients. Cocoon is the metamorphosis stage of transition from larva to adult insect. Adult insect is the reproduction stage to mate, lay eggs and breed future generations. During the entire lifespan, it only feeds in larva stage and stores nutrients for life activities during cocoon and adult insect stages. Silkworm belongs to oligophagous insects.
Other than its favorite mulberry leaves, it also eats tricuspid cudrania leaves, elm leaves, root of Austrian serpentroot, dandelion, lettuce leaves, etc. Essential nutrients for silkworms include protein, carbohydrate, fat, vitamin, inorganic salt, water, etc. Mulberry leaves are the most suitable natural food substances for silkworms. After eating mulberry leaves, larva silkworm grows rapidly. Under suitable temperature, a silkworm sheds a skin every 6 to 9 days, in total takes about 24 to 32 days, eats 20 to 30 gram mulberry leaves (dry substance 5 to 6.2 gram) and normally undergoes four times of dormant skin shedding from hatching to become cocoon and spin silk. When it reaches growth limits, its weight increases by about 10000 times. Spinning silk and making cocoon are natural abilities of a silkworm to suit the environment and survive. Silkworm cocoon can be used to reel silk. Silk is the precious raw material for spinning and weaving. It is also widely used in military and telecommunication. The cocoon, moth and feces of silkworm can also be comprehensively utilized as raw materials for many chemical industries and medicine industries. They can also be used as nutrients for plants.
By Shane Lee
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