ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

How Silk is Made by Silk-worms?

Updated on September 7, 2013

Though various species of insects produce silk, which is a secretion of their salivary glands, silk of commercial quality is produced only by a very limited number of species. The silk produced by the mulberry silk worm of the species Bombyx mori is the most valued of these. This species belongs to the family Bombycidae. This silk is one of the most valuable and widely used products. It is the secretion of the paired salivary glands of the full grown last larval stage of the silk moth Bombyx mori (Fig. 17.5). The worm feeds on mulberry leaves (Morus aha).

The adult moth is creamy white about 5 cm across with fully spread wings. From head to the tip of the abdomen, it measures about 3 cm. The wings are however feeble and the insect scarcely flies. As adult it takes no food and lives for only 2-3 days during which the female lays 300-500 eggs. The eggs hatch into tiny larvae by 8-12 days. These feed on mulberry leaves and grow in size. They molt four times to reach full grown size of about 8 cm in length. It is grayish and has a hump behind the head and a spine-like horn at the hind end dorsally. Full growth is reached by 28-30 days. When full grown it becomes restless and spins a cocoon.

Spinning of Cocoon

Spinning of cocoon takes about 3 days. During this operation the head is constantly moved from side to side swiftly at the rate of about 65 times per minute. As this larva does so, the secretion of the salivary gland is continuously poured out through the common opening at the tip of a median cylindrical spinneret on the lower lip or labium.

This is a clear viscous fluid, but as it is exposed to the air it hardens into the fine silk fiber. This fiber forming the cocoon is continuous and ranges in length from 700 to 1100 meters. Silk consists of two proteins: fibroin and sericin. The silk thread is elastic, resistant and non-conductor of heat and electricity. It has also good tensile strength, comparable to steel. The cocoons are oval. The color of the silk varies from white to a beautiful golden yellow.

Time Lapse Spinning Cocoon


The larva pupates within the cocoon. The cocoon is made up of a single reel-able thread. The pupa is the inactive stage undergoing transformation to become adult moth. The adult moth emerges from the cocoon after 10-12 days. While coming out it softens one end of the cocoon by an alkaline secretion which enables it to break through the strands of silk. Such cocoons through which the moths emerge are called pierced cocoons. These are of low value because they cannot be reeled.


For reeling (winding the thread on a wheel), the cocoons are gathered about 8 days after spinning begins, and the pupae are killed usually by heat from steam or hot air or even by fumigation and then thoroughly dried. Next, the cocoons are immersed in warm water. This loosens the fiber. The fibers from four or five cocoons are caught up together and twisted into a thread that is wound on the reel.

History of Silk

Usefulness of silk was first discovered by Empress Lotzu in China about 2700 B.C. Since then silkworms were reared and silk was produced in that country as a monopoly for about next 2000 years. In the year 550 A.D. two European monks smuggled out eggs of silk moth and thus introduced silk culture in Europe.

Today, sericulture, or the commercial production of silk, is an important industry in several countries including China, Japan, India, France, Spain and Italy. In India the mulberry silk is produced extensively in Karnataka, Tamil Nadu, Assam, West-Bengal, Jammu-Kashmir and Punjab.


    0 of 8192 characters used
    Post Comment

    No comments yet.


    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)