The Similarities Between Silkworms & Mulberry Plants

Silkworm Identification

• Silkworms are no longer found in the wild, since the adults are unable to fly and have no natural defenses against predators. Adult silkworm moths have an approximate 2-inch wingspan, with four scaly, cream-colored wings and brown markings. The females are usually larger in size than males, with larger abdomens, while the males sport hairy, eyebrowlike antennae. The young larvae have hairy wormlike bodies, with a small horn on the back end, and three distinct body segments, as well as six clawed and jointed legs that help them climb and cling to mulberry plants. Their bodies become smooth as they molt and mature.

Eggs and Young Silkworms

• Female silkworms lay small eggs in late summer or early fall. The insects overwinter as eggs and hatch in the spring, just as mulberry trees begin to produce new leaves and catkins, or petalless flowers. Traditionally, silkworms eat only mulberry leaves and catkins, although as of 2011, commercial silkworm growers have developed artificial silkworm diets. The tiny 1/8-inch insects require new foliage from mulberry trees to survive and cannot eat tough or mature leaves until they grow.

Pupa and Adults

• The larval insects devour large quantities of mulberry leaves as they mature. They do not wander off in search of food, so silkworm producers must supply them with a regular supply of leaves. These insects molt five times and eventually become around 2 inches long. Mature larvae pupate in cocoons made of fine yellowish or white silk for approximately three weeks before emerging as adults. The adult moths, which do not eat, live only long enough to mate and lay their eggs before dying.

History

• Silkworm production began in China and later spread to other parts of Asia, including Japan and Korea. In the 11th century, European merchants joined the silk trade by stealing mulberry seeds and silkworm eggs and exporting them to Europe. During the 18th century, growers in the United States attempted to cultivate silkworms using both native mulberry species, such as the red mulberry, as well as exotic species, such as white or Russian mulberry trees. But silkworm farmers soon discovered that the climate in North America would not support large-scale silk production and abandoned the enterprise.