Golden Muga Silk: Assam's Endangered Luxury Fiber Worth Its Weight in Gold

Written by Chandra Wong

Exotic items have been so coveted through the centuries that explorers traversed continents or thousands of nautical miles in search of their prize. The desire for spices and silk opened up much of the trade between Asia and the west. Silk is a luxurious fabric once only available to royalty. Muga silk is extravagant and elusive even amongst other silks. It is one of the most elegant and valuable natural fibers.

An Exclusive Tradition

Muga silk is produced exclusively in the northeastern state of Assam in India. ‘Muga’ translates to amber from Assamese as this silk has a golden-yellow hue and comes from the cocoon of the muga silkworms. To make this unique and highly prized fabric, skilled workers must unwind a muga caterpillar’s cocoon into a single long seamless thread. To make just one sari, a traditional use of this special fabric, about one thousand cocoons need to be unraveled.

A sari made of muga silk can cost up to $6500, thousands more than other saris. Some of the most intricate fabrics made from regular silk cost $250 in India, but the same design on muga silk can increase the price into thousands of dollars! Muga is so central to the culture in the Assam region that there’s even a traditional song about the golden thread. Muga silk is unique because of its naturally lustrous gold color. The color is actually enhanced after washing instead of fading that occurs with most fabrics. It can last up to 100 years and offers protection from the sun by absorbing up to 85% of harmful UV rays. 

Muga Cocoons. Image via swadesi.org

Farming Silkworms

Muga farmers, called rearers, sort cocoons by several criteria. Cocoons that will be used in rearing where moths are allowed to mature and emerge from the cocoons are known as seed cocoons or just muga seeds. Tradesmen have to purchase the expensive seed cocoon from different parts of the northeast of Assam. The high price is because of the limited availability of the muga seeds as well as the huge amount of manual labor needed to raise and propagate the muga silkworms. Muga silkworms live and feed on their host plants, Som and Soalu. Silkworm farmers collect the cocoons, wait for the moths’ emergence, and work in the Som gardens year round. 

The hatched cocoons are used for rougher fabrics such as winter clothes and blankets. This is because the silk thread is torn as the moth emerges from the cocoon. The resulting threads are therefore shorter and rougher. The highest quality, and thus most expensive, muga silk comes from unhatched cocoons. The unhatched cocoons can be unraveled into one continuous thread. Muga silk weavers production is limited both by the limited number of unhatched cocoons and the need for a large quantity of these cocoons. 

Muga has been highly prized for centuries. Historical records reveal that exquisite varieties of muga silk were sent by king Bhaskara of Kamrupa (Assam) to king Harshavardana over 1,300 years ago. Chinese records dating back to 248 CE mention trade routes to Assam for this silk. While still currently a cherished and valuable fabric, the muga silkworm rearers and weavers producing the silk are both facing losses. Their earnings have not significantly increased since 2015, yet the price of the cocoons has gone up 50%. 

A Bihu dancer in a traditional muga silk mekhela-chador. Image via outlookindia.com

Spinning Into Gold(en) Thread

Approximately 1,000 cocoons are needed to produce 7 ounces of yarn, the amount needed to produce about one sari. It can take up to a week to reel the golden thread into yarn. When preparing the cocoons for unraveling, the Assamese traditionally add dried banana peel or patty thatch ash to the washing mixture. This degums the cocoons and gives the thread a better sheen. For muga, the shiniest silk yields the highest prices. 

The process of unraveling and spinning the muga silk into thread or yarn is called reeling. Two people then use a Bhir or Bhawrii to carefully wield the long muga silk threads in a continuous motion. Reelers gently pull from several cocoons and join the thin strings together to make one thicker thread. They must make sure each thread has a consistent thickness. Finally, the yarn is loaded onto bamboo looms for Assamese women to weave it into the desired fabric. Only about 45% of the silk filament is reeled and the rest is rejected as waste. This labor-intensive process only allows about 100 grams of raw silk to be reeled by two people in a day. 

Muga moth. Photo: Dr Richard Peigler. Image via floridamuseum.uft.edu

The Very Hungry Caterpillar Meets Rumplestiltskin

Muga moths are multivoltine, producing six broods in a year. Only two of these broods make cocoons suitable for high quality fabrics.  The entire lifecycle of the muga moth lasts for about 50 days in the summer and about 120 days in the winter. The muga moths are only semi-domesticated and are raised outdoors. Like all other silkworms, their life cycle consists of egg, larva (caterpillar), pupa (within a cocoon), and adult (moth) phases.  

To breed the muga moths, adults that have just emerged from their cocoons are allowed to mate and, in the coupled state, the pair is tied with a piece of cotton thread to a stick that is about 2 feet long and made of dried straw, thatch, grass, or twine which is known as Kharika.  This is where the female will lay her eggs. Rearers then transfer the Kharika to a Som tree. Here, tiny ash-colored eggs hatch and larvae emerge that are about 2 mm long (1/16 - ⅛ inch). These larvae begin to feed on the leaves.

Like the titular character in Eric Carle's famous children's book, these caterpillars/larvae have a voracious appetite. The larvae are vulnerable at this stage so the farmers need to keep a watchful eye to ensure they can form the cocoons needed to make muga silk. Farmers use slingshots to launch clay pellets into the fields to keep potential predators at bay. Over the next 1-2 months the larvae molt four times and grow to a length of 30 mm (1-3/16 inch). The caterpillars then search for a suitable location for cocooning. 

The mature caterpillars are collected at night and they are put into a Jali for cocooning. A jali is made by tying together semi-dried leaves of the Som trees. Here the caterpillars rest and weave their cocoons over a period of three days until they fully empty their silk glands. This is when they enter pupation. After 7 days in the summer and 10 days in the winter, the cocoons are harvested and sorted. Commercial growers use ovens to kill the pupa and preserve the cocoons for reeling at this time. But, not all cocoons are used for silk. Some are stored in the chaukori pera, a bamboo box that allows farmers to continue propagation of the muga silkworm. 

Hand loom: in the process of weaving a mekhela-chador from muga silk. Image via outlooktraveller.com

Climate Change Endangers Muga Silk Production

While muga farmers work tirelessly to make sure the moths survive, it is not entirely within their control. The muga moth is threatened by the climate crisis. Muga silkworms are reared outdoors and exposure to even the slightest change in temperature or humidity can wreak havoc on the muga life cycle. Farmers had to delay rearing for ten to fifteen days during a heatwave in 2018 to avoid silkworm deaths. 

Losing this time during peak commercial season when production should be ramping up means producers can end up with less muga silk to sell. A second major threat to the muga silkworms is pollution. The pollution is created by nearby tea gardens and petrochemicals. The tea gardens use pesticides and herbicides that have toxic effects on the muga moth that impact its ability to reproduce and can kill the moths. This pollution has more of an impact on muga silk compared to other high-end Indian silks like mulberry silk. 

Image via ibef.org, source: Central Silk Board of India

Challenges For The Future

There are four types of silk produced in India and less than 1% is muga silk.  Although 239 metric tons of muga silk was produced in India in 2021, this doesn’t meet the global demand and this drives the price higher. The limited supply of authentic muga silk has led some producers to fill the gap with fakes. In 2007, the Indian government designated Assam muga silk as a protected geographical indication (GI) product to combat the influx of fake muga. This means authentic muga silk can only come from Assam. This designation, however, has not increased the production of muga. Experts predict that all of the habitat area of the muga silkworm host plant sectors will be totally lost by 2046  due to the climate crisis.

While traditionally used for garments of royalty and other very wealthy people, the high tensile strength and load-bearing capabilities of muga silk makes it adaptable to non-traditional uses. This strength and durability carry over when It is embedded in aircraft tires, used in parachute ropes, and bulletproof vests. Muga is also being studied in biomedical applications for tissue (bone, cartilage, etc.) regeneration.

Both traditional and newly discovered applications for muga silk make it an important, and expensive, product. Muga farmers and their clients are relying on environmental conservation efforts to save the host plants and the muga silkworms. The survival of this millennia old fabric and the livelihoods of many in Assamese depend on this delicate insect.