silkworm

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silkworm,

name for the larvalarva,
independent, immature animal that undergoes a profound change, or metamorphosis, to assume the typical adult form. Larvae occur in almost all of the animal phyla; because most are tiny or microscopic, they are rarely seen. They play diverse roles in the lives of animals.
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 of various species of moths, indigenous to Asia and Africa but now domesticated and raised for silksilk,
fine, horny, translucent, yellowish fiber produced by the silkworm in making its cocoon and covered with sericin, a protein. Many varieties of silk-spinning worms and insects are known, but the silkworm of commerce is the larva of the Bombyx mori,
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 production throughout most of the temperate zone. The culture of silkworms is called sericulture. The various species of silkworms raised today are distinguished by the quality of the silk they produce, the type of leaves on which they feed, and the number of breedings per year. The most widely raised type and the producer of the finest silk is the larva of Bombyx mori, of Asian origin. After centuries of domestication, Bombyx mori is no longer found anywhere in a natural state. The legs of the larvae have degenerated, and the adults do not fly. Hatched from eggs so small that about 35,000 of them weigh only an ounce, these silkworms are immediately quite active and feed voraciously on mulberry leaves. At the end of the larval stage (32 to 38 days after hatching) they are about 3 in. (7.5 cm) long. A mature larva attaches itself to a twig and, with a weaving motion of its head and a slow, circular motion of its body, begins to spin its cocoon (see pupapupa
, name for the third stage in the life of an insect that undergoes complete metamorphosis, i.e., develops from the egg through the larva and the pupa stages to the adult.
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). A moist substance, fibroin, is manufactured in two silk glands located on the underside of the larva's body; mixed with a small amount of wax, it is emitted from an orifice called the spinneret, in the lip of the larva. The fibroin dries quickly in the air, hardening into a half-mile-long thread of silk that makes up the cocoon. The adult moth, with a wingspread of 1.75 in. (4.5 cm), emerges from the cocoon in about two weeks. The moths mate and lay their eggs (several hundred from each female) within a week; the eggs hatch in about ten days. Only enough cocoons to ensure adequate reproduction are allowed to hatch; the rest are unwound after developing for a week, and the silk is processed. The giant silkworms used in some Asian and South American sericulture are the larvae of the closely related saturnid moths (family Saturniidae). They include the tussah moth (Antherala pernyi), the producer of tussah silk. The ailanthus moth (Samia walkeri), a large, olive-green saturnid moth used in China to produce a coarse grade of silk, was imported to the United States along with its food plant, the Chinese ailanthus tree, as the basis of an industry that never materialized; the moth has been firmly established in the New York City area since 1861. Diseases of silkworms have occasioned important scientific work. When Pasteur saved the French silk industry from destruction by pébrine, a protozoan disease of insects, in the mid-18th cent., he also made an important contribution to the germ theory of disease. The common silkworm, Bombyx mori, is classified in the phylum ArthropodaArthropoda
[Gr.,=jointed feet], largest and most diverse animal phylum. The arthropods include crustaceans, insects, centipedes, millipedes, spiders, scorpions, and the extinct trilobites.
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, class Insecta, order Lepidoptera, family Bombycidae.

silkworm

[′silk‚wərm]
(invertebrate zoology)
The larva of various moths, especially Bombyx mori, that produces a large amount of silk for building its cocoon.

silkworm

1. the larva of the Chinese moth Bombyx mori, that feeds on the leaves of the mulberry tree: widely cultivated as a source of silk
2. any of various similar or related larvae
3. silkworm moth the moth of any of these larvae
References in periodicals archive ?
Genetically engineering silkworms --which for centuries have been used to produce silk for textiles and some other uses--eliminates the need for those costly spinning technologies.
Silkworm breeders of Uzbekistan have prepared 26,000 tons of cocoons; the rate increased by 1,000 ton compared to last year, the Ministry of Agriculture and Water Resources reported.
1 After silkworms hatch from eggs, they're raised in bamboo trays.
The project, which used Fraser's piggyBac vectors to create transgenic silkworms with both silkworm and spider silk proteins, was a collaboration of his laboratory with Donald Jarvis and Randolph Lewis at the University of Wyoming.
Mulberry varieties regarded as one of important factors that affects on number of laid eggs, fecundity, hatchability, larval period and weight in local strains and obtained hybrids in silkworms.
Baddour indicated that the Ministry of Agriculture has taken several measures to preserve silkworms and to increase their production through establishing a number of specialized centers.
Vermibeds were prepared in rectangular troughs of 45 cm x 35 cm x 15 cm size with six replicates using the silkworm litter and pre-decomposed leaf litter in the proportion of 0+100%, 25+75%, 50+50%, 75+25% and 100+0% respectively.
These results indicate that silkworms have skillfully adapted to the defense mechanism of mulberry leaves.
It's not long before problems arise: raising money to buy the silkworm eggs, finding mulberry leaves (the only thing silkworms will eat) and, worst of all, realizing that to extract silk from the cocoons, the pupae inside must be boiled alive.
When Kaplan and Jin analyzed the glands of silkworms and their fibers, they found similar structures.
The GM silkworms spin tough fibres containing spider silk proteins that are more elastic and extensible, making it more suitable for use in a range of medical applications, the Daily Mail reported.
Silkworms normally hatch during the spring and their natural food is the leaf of the mulberry tree.