How is Silk Made by Silkworms? Procedure & Silk Types

Silk is among the most luxurious and expensive fabrics globally. It originates from the cocoon of silkworms, Bombyx mori and is well-known for its smooth and slippery texture. Currently, people have commercialized the practice of keeping silkworms for silk. However, the majority of the individuals do not clearly understand how silkworms make silk. Also, some fail to understand which silkworm species produce silk.

Silk is made by silkworms when they spin a cocoon around them before becoming silkmoths. The fibers of the cocoon are harvested by boiling them in hot water or hot air to kill the silkworm pupa then unravel the silk for further processing. Many silk types are made from different silkworm species.

Silk manufacturing is delicate and turning the silk strands into fabric that can be worn is an expert’s job. Silk is made of a protein fiber which is common among insect larvae that secrete it when forming cocoons. However, what you feed the worms determines the quality of the silk significantly.

How is Silk Made by Silkworms

Are There Different Types of Silkworms?

There are over 500 species of silkworms globally. However, very few species are used for silk production. Commercially kept silkworm species are Bombyx mori, typically killed before pupae emerge.

They are killed by piercing cocoons with a needle or dipping them in boiling water. This allows the whole cocoon to disentangle as a single continuous thread. This allows an even cloth to be made from silk. You can breed silkworms on your farm quite easily.

Bombyx mori is well known to produce more fine silk than other wild species. Wild silks are harvested after moths leave the cocoon. The process involves cutting threads hence there is no long thread-like commercial production. Among the most famous wild species that produce silk are Muga, Eri, and Tasar silkworms. Notably, all these species have varieties and textures of silk.

How is Silk Made by Silkworms?

The process of silk production from silkworms is called sericulture. 

What is Sericulture?

Sericulture is the process of rearing silkworms for commercial silk production. It is a long process where silkworms are raised from eggs to cocoons.

This process involves looking after silkworms and feeding them with leaves from a specific Mulberry plant. Farmers are encouraged to provide adequate food to the silkworms during their larval growth stage for enhanced metamorphosis.

Therefore, maintaining these plants is involved (Mori culture). However, some silk threads are produced by wild and semi-wild silkworms. These silkworms feed on leaves of Oak and Som in open forests.

After silkworms have completed their larval cycles, they turn into pupae. This is similar to chrysalis in butterflies. This happens after they wrap up themselves with fine threads in a cocoon.

Farmers conduct the harvesting process when pupae reach the maturity phase (before the moth emerges). This process is called rearing. You can easily get rid of silkworms if you don’t need them or they infest your farm.

Step by Step Procedure of Silk Production from Silkworms

Silk is produced from silkworms in the following stages:

Step 1: Mulberry Silk Rearing

Mulberry forms 95% of the world’s silk production. This silk comes from Bombyx mori silkworms’ moths that feed on leaves of the mulberry plant, Morus indica. These plants are perennial bushes that have wide-spreading branches. They are ideally planted, manured, and catered to supply silkworms’ food.

Rearing Mulberry silkworms requires appropriate equipment, temperature, space, and humidity. Therefore, to meet these conditions, unique rearing houses are constructed.

Silkworms are reared on shelves of raising trays arranged on tiers of up to 10. This method is cost-effective as it allows a vertical arrangement of trays, placing more eggs in a limited space. ‘Shoot’ rearing is another method that can be used to accommodate 2 to 3 tiers of specific dimensions. Also, there is a floor method where silkworms are reared on a high platform above the floor.

To feed larvae, mulberry leaves are chopped into small pieces. Silkworms are fussy and heavy feeders, so great care can be enhanced by supplying them with the right food at various maturity intervals. Young worms require tender leaves. Also, the leaves should have no wetness.

Silkworms’ life cycle is divided into instars. Since they are heavy feeders, the larvae shed their skin, growing big. Notably, they can grow 10,000 times their birth size. The pinhead stage is the first instar stage that occurs as soon as eggs hatches. Subsequently, the first molt takes place. The final stage is the blue egg when the waste is excreted, turning translucent, then yellow. 

Larvae are taken and placed in ‘Chandrika’ (trays) at the blue egg stage, forming cocoons. Silkworms take 10 days to emerge as fully-grown adult moths. In mulberry silk, moths cannot emerge as moths out of the cocoons. Therefore, the moth is killed before they come out of the cocoon to form a long and continuous thread.

Step 2: Reeling, De-gumming, and Twisting

Silkworms are usually killed by dipping them in boiling water or exposing them to hot air chambers then threads are reeled. At this stage, threads are untwisted and they contain sericin, a protein coat. This is still a raw thread that needs more process.

Sericin is removed by loosening cocoons by boiling. The resulting floss is pulled then thread ends are gathered and twisted. De-gumming is the process of eliminating sericin from threads. Later, threads are twisted as raw silk becomes silk yarn made into hanks or skeins.

Step 3: Mulberry Silk Weaving

Silk weaving is the process of bringing silk pieces together to form a fabric. Silk can be woevn as a satin weave, open weave, and plain weave. Two threads would be woven together to form a warp (up and down) and weft (across) pattern.

Silk weaving is more traditional in Northeast India, with Sualkuchi in Assam serving as the primary silk manufacturing town. They produce conventional Assamese garments, saris, and Khasi jainsems and dharas. The expert weavers can weave intricate motifs of any complexity. One of them is mulberry silk weaving.

Step 4: Printing

The woevn sil is then printated either through digital priting or screen printing to attain the desired look.

Step 5: Finishing

Finishing adds other qualities to the silk such as fire proofing, shiny surfaces and crease-proofing it.

Is Silk vegan?

Vegans oppose the mistreatment of silkworms in silk production. Unlike the commercial silk production by domesticating Bombyx mori, Ahimsa silk is peace silk that does not unreel the cocoons. 

Eri silkworms are used to produce Ahimsa silk where it leaves a small opening in the cocoon, which they crawl as moths. This process allows the 10 days of larvae molting with better-quality silk than domesticated silkworms.

Silkworms can be eaten by bearded dragons and other reptiles. Humans also consume silkworms reducing the impact of boiling them for silk.

Vegan Silk Alternatives

Although you may opt to buy Ahimsa silk that does not mistreat animals, Ahimsa silk as well exploits animals in ways that vegans strongly oppose. The best alternative to avoid contributing to the mistreatment of silkworms is to buy other products made of different materials rather than silk. The available options are:

  • Cruel-free, cheap plant-based materials such as nylon, polyester, and rayon efficiently replicate silk and are widely available.
  • Rayon is a natural wood pulp fiber comprised of cellulose dyed in various colors. However, it, like polyester and nylon, may be exposed to many non-environmentally friendly chemicals throughout the manufacturing process.
  • On the other hand, Lyocell and modal are rayon fibers that have been colored without the use of hazardous solvents. They are made using environmentally friendly components and are produced in a closed-loop system. This means that the chemicals are continuously accessed and reused. Tencel is a type of Lyocell approved to be created from environmentally friendly wood pulp. As a result, it is a considerably more environmentally friendly fabric alternative.
  • Lotus silk is a form of silk made from lotus flowers and is considered one of the most eco-friendly fabrics in the world.
  • Ramie is also a flowering plant used to produce fabrics that can be used in the place of silk from silkworms.
  • Bamboo silk is another alternative to animal-based silks which are used all over the world.

While there may be no perfect alternative in this scenario, synthetic alternatives prevent millions of animals from dying.

Bottom Line

It is evident from this article that silk thread is nothing more than a protein fiber that is created by silkworms. Bombyx mori species of silkworms are mainly used in commercial silk production. Silkworms should be supplied with mulberry leaves that enhance larvae development for more silk production. Notably, there are numerous species of silkworms of various uses to explore.


University of California. How is silk made?

The University of Rhode Island. Silk and Silkworms.

University of California. Is silk made of living thing?

Leave a Comment