Common names: Eri silkworm, Ailanthus silkmoth, Cynthia moth, Tree of heaven, Silkmoth, Ricini moth, Niang ryndia (Khasi) 

Scientific name: Samia Cynthia, Drury, 1773 

SPECIES CHARACTERISTICS

Eggs are ovoid and candid white. Larva is greenish yellow changing to pure yellow by the third day.  From the third instar the body color changes from yellow to cream, green, blue, or white.  The larvae are either spotted or unspotted.  A white powdery substance covers fully mature larvae.  The cocoon is distinguished from other species by its elongated, soft wooly, white, and peduncleless characteristics.  Furthermore, the cocoons do not produce a continuous thread.  Male moths reach a length of 2.3 cm and females reach 3 cm.  Average wingspan is 13-15 cm respectively for male and female S. cynthia moths. This species may produce up to 5-6 generations per year when domesticated whereas the wild relatives have 1-3 generations per year. S. cynthia larvae feed primarily on the castor plant (Ricinus communis L.), which can also be utilized to make castor oil, and kesseru (Heteropanax fragrans Seem.)

HABITAT & RANGE

Native to Assam, India and domesticated throughout India, China, and Japan.

FASCINATING FACTS

Samia cynthia are domesticated for silk production as well as for consumption in the larval and pupa stages by humans and as feed for domesticated animals.  Live larvae are sold in markets for up to INR 160/ kg (USD 2.55/ kg ) in North-East India.  The delicacies are roasted, fried, or boiled before consumption.  In addition to their high protein content, some regard the caterpillars to have medicinal properties.  The by-products of the eri rearing are often used as fertilizer for agricultural production.

Like other silkworms, Samia cynthia is highly regarded for the silken cocoons spun by the larvae in which it carries out its final stages in its lifecycle to become a moth.  However, S. cynthia differs from other domesticated silk producers in a few ways.  The cocoon does not contain a continuous thread around the pupae and therefore is often treated like cotton or wool in weaving.  The larval and pupa stages are considered a delicacy in Northeast India making the silk more or less a by-product.  Eri silk is considered to be a peaceful product because the moth leaves through an opening in the bottom of the cocoon before it is harvested for weaving unlike the more prominent Bombyx mori silkworm, which has a cocoon that must be processed and unraveled while the insect is still in the pupa stage.  The eri silk which results is often darker than other silks and tends to provide cloth that has a warmer touch.

ANNE PATRIE LYNGDOH, MSC

Anne's education is in Ethnobotany with research interests in subsistence agriculture, food systems, and sustainability.  Her most recent studies took her to North-East India where she worked with small-scale rice farmers and conservers of traditional foods

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