If the world were to vote for the pickiest eater, the silkworm would easily win. For thousands of years, this tiny creature has adhered to an ironclad rule: it loves only mulberry leaves. This isn’t just a taste preference; it’s a biological instinct etched into its DNA.
Surprisingly, this “picky eating” habit is precisely what makes one of the world’s most luxurious fabrics possible. Without the silkworm’s stubborn commitment to mulberry leaves, the legendary supple texture of Chinese silk simply wouldn’t exist.
The Evolutionary Path of a Fussy Eater
The silkworm’s relationship with the mulberry tree began approximately 18 million years ago. Initially, mulberry trees were tropical evergreen giants. Over millions of years, they migrated to temperate zones, evolving into the lush deciduous trees we see today.
While other insects nibble on roots and bark, silkworms focus solely on mulberry leaves. Interestingly, silkworms aren’t born with an exclusive preference for mulberry – physiologically, they can digest elm, fig, or willow leaves. However, after generations of thriving exclusively on mulberry trees, they’ve developed a hereditary “mulberry leaf complex.”
The Scent-Guided Navigation System
How do tiny larvae pinpoint their exclusive feast? With an extraordinary sense of smell. Scientists have isolated mint-like volatile oils from mulberry leaves. Even from 30 centimeters away (which is quite a distance for a minuscule larva), silkworms can precisely detect the scent and quickly follow it to their meal.
This biological “GPS” system is the cornerstone of silkworm propagation. By absorbing the unique nutrients from mulberry leaves, silkworms can spin delicate yet strong silk threads, weaving them into silk scarves that are as soft as clouds and yet incredibly durable.
Six Millennia of Civilization in Threads
The history of silk is, in essence, a history of human civilization. At the Shicun site in Shanxi, archaeologists recently unearthed six stone pottery silkworm pupae. These 6,300-year-old relics confirm that humanity began to revere silkworms and mulberries even at the dawn of civilization.
Further south, the discovery of silk traces in the Sanxingdui sacrificial pits reveals that for the ancients, silk was not merely clothing but also a spiritual medium for communicating between heaven, earth, and humanity.
