Muga silk is a rare, indigenous variety of silk prized globally for its naturally shimmering color and exceptional durability. This fiber is unique to the Brahmaputra Valley of Assam, India, and is often called the “golden silk” of the region. It is one of the four types of wild silks, yet its production is confined to a specific geographical area, making it one of the most exclusive textiles in the world.
The Muga Silkworm Antheraea assamensis
The production of Muga silk begins with the semi-domesticated silkworm, Antheraea assamensis. Unlike the fully domesticated silkworm, Bombyx mori, the Muga silkworm is still largely wild and is highly sensitive to environmental changes and pollution. This insect is endemic to the North-Eastern region of India, thriving in the warm, humid climate of the Brahmaputra Valley.
The silkworm is multivoltine, completing four to five life cycles, or “crops,” annually, with the entire life cycle lasting about 50 days in summer and extending up to 120 days in winter. The larval stage, which is responsible for the silk production, is spent feeding voraciously on specific host plants in the open air.
The diet of A. assamensis is highly specialized, consisting almost exclusively of the leaves from two primary host trees: Som (Machilus bombycina or Persea bombycina) and Soalu (Litsea polyantha). The chemical compounds within these aromatic leaves are directly responsible for the characteristic color and strength of the resulting silk fiber. The larvae are reared outdoors on these specific trees, which ties the production of Muga silk closely to the ecology of the region.
Distinct Properties of Muga Silk
The defining characteristic of Muga silk is its striking natural golden-yellow color, which is directly derived from the silkworm’s specialized diet. This unique pigmentation is chemically stable, giving the fiber an inherent resistance to fading. The silk is a protein-based fiber that exhibits a high degree of luster, which, unlike most textiles, actually improves and intensifies with every wash.
Muga fiber is also celebrated for its exceptional mechanical properties, particularly its high tensile strength, which surpasses that of many other natural silks, including Mulberry silk. This makes the fabric extremely durable and long-lasting.
Beyond its strength, the silk possesses natural hypoallergenic and antibacterial qualities, making it suitable for sensitive skin. It also offers a degree of protection against environmental factors, absorbing up to 85% of harmful ultraviolet (UV) radiation. The silk’s structure lends itself to a comfortable, breathable textile that is soft to the touch despite its inherent toughness.
Traditional Muga Sericulture
The sericulture process for Muga silk is distinct from that of domesticated silks because A. assamensis is reared in a semi-wild, open-air environment. After the female moth lays its eggs on a straw structure called a kharika, the newly hatched larvae are transferred and hung on the branches of the host trees, such as Som and Soalu. The larvae spend their entire feeding stage on the trees, which are often in fields or forested plots, requiring constant protection from predators and adverse weather.
Once the larvae are fully grown, or “ripe,” they descend from the trees and are collected by the rearers. They are then placed inside specialized baskets called jali, providing a protected space for them to spin their cocoons. The spinning process takes a few days, after which the cocoons are harvested.
To prevent the pupa from emerging and breaking the continuous silk filament, the cocoons must be stifled, traditionally done through sun-drying or smoking, although modern methods use hot air ovens. The next critical step is reeling, which involves boiling the cocoons in an alkaline solution, often containing soda, to soften the sericin gum that holds the fiber together. This cooking process allows the thread to be unwound.
The silk is extracted using a traditional, hand-operated reeling machine known as a Bhir. This labor-intensive process typically requires two people and is extremely slow, yielding only about 60 to 80 grams of raw silk per day. Each individual cocoon provides a single, continuous filament that can measure between 350 and 550 meters in length.