- Bombyx mori, commonly known as the silkworm, is a domesticated species of moth belonging to the order Lepidoptera and the family Bombycidae. It is one of the most economically valuable insects in human history due to its role in the production of silk, a natural protein fiber that has been prized for thousands of years. Native to northern China, B. mori has been cultivated for silk production for over 5,000 years, and through long-term domestication, it has become completely dependent on humans for survival and reproduction. The species no longer exists in the wild in its original form, distinguishing it as one of the earliest and most fully domesticated animals.
- Adult Bombyx mori moths are medium-sized, typically 2.5 to 3 centimeters in length with a wingspan of about 4–6 centimeters. Their bodies are stout and covered with creamy white scales. Unlike most moths, adult silkworm moths have reduced mouthparts and are incapable of feeding, surviving only a few days after emergence for the sole purpose of reproduction. Their wings are broad but weak, and they are incapable of sustained flight due to thousands of years of selective breeding under human care. Males can be distinguished from females by their smaller size, narrower abdomens, and more feathery antennae used to detect female pheromones.
- The life cycle of Bombyx mori is a classic example of complete metamorphosis, consisting of four distinct stages: egg, larva (caterpillar), pupa, and adult. The cycle begins when the female lays 300–500 small, oval eggs, which may remain dormant for several months under cool, dry conditions before hatching. Upon hatching, the larvae—known as silkworms—are about 2 millimeters long and feed voraciously on the leaves of the mulberry tree (Morus species), their exclusive food source. The larval stage lasts about 20–30 days, during which the caterpillar passes through five instars (molts), growing to a length of about 7–8 centimeters.
- At the end of the fifth instar, the larva stops feeding and begins the spinning stage, secreting a continuous filament of silk from specialized glands called sericteries. This filament, composed of the proteins fibroin (core fiber) and sericin (a gummy coating), is extruded through the spinneret near the mouth. Moving its head in a figure-eight motion, the larva spins a cocoon around itself, which serves as a protective casing during pupation. The silk filament can reach a length of up to 900 meters from a single cocoon. Inside the cocoon, the larva metamorphoses into a pupa, eventually developing into an adult moth in about 10–14 days.
- In commercial sericulture, cocoons are typically boiled or steamed before the adult moth can emerge. This process kills the pupa and allows the silk filament to be unwound in a continuous strand. If the moth emerges naturally, it breaks the filament, reducing its economic value. The silk produced by Bombyx mori is renowned for its luster, strength, and smooth texture, making it one of the most luxurious and sought-after natural fibers in the world. The global silk industry, centered historically in China, India, and Japan, continues to rely on this species as the primary source of raw silk.
- From a biological and genetic standpoint, Bombyx mori has been extensively studied as a model organism in developmental biology, genetics, physiology, and biotechnology. Its genome has been fully sequenced, revealing approximately 14,000 genes across 28 chromosomes. Studies on B. mori have provided insights into hormonal regulation, metamorphosis, and silk protein synthesis. Advances in genetic engineering have also enabled scientists to modify silkworms to produce silk with novel properties or incorporate foreign proteins for biomedical applications, such as tissue engineering and drug delivery.
- Ecologically, Bombyx mori is a fully domesticated species and cannot survive independently in the wild. It depends entirely on human cultivation for food, shelter, and reproduction. However, its wild ancestor, Bombyx mandarina, still exists in parts of East Asia and is used in hybridization programs to enhance silk yield and disease resistance.
- In cultural and historical terms, Bombyx mori has had a profound impact on human civilization. The development of sericulture in ancient China led to the establishment of the Silk Road, which facilitated trade and cultural exchange between East and West for centuries. Silk became a symbol of wealth, status, and international commerce, shaping economies and empires.
