What else do silkworm babies eat besides mulberry leaves during their growth?

“Spring silkworms should not grow old, spinning silk day and night. Why begrudge their tiny bodies' end, for tangling and twining has its time.” This is the "Silkworm Silk Song" written by Bao Linghui of the Southern and Northern Dynasties. A silkworm's life goes through silkworm eggs—newly hatched silkworms—mature silkworms—silkworm cocoons—silkworm moths, totaling more than forty days, showing that the growth process of silkworm babies is very brief.

I. The growth process of silkworm babies

1. The silkworm babies newly hatched from eggs are black like ants, which we call “newly hatched silkworms.” Their bodies are covered with fine hairs, and after about two days the hairs become inconspicuous. About 40 minutes after hatching from the eggshell, the silkworm has an appetite, and at this point the feeding process must begin.

2. Silkworm babies live on mulberry leaves. After continuously eating mulberry leaves, their bodies slowly turn white, and after a period of time they begin to molt. Molting takes about one day, during which they neither eat nor move, like sleeping; this is called "dormancy." After one molt, they become second-instar larvae. Each molt counts as one year of age, and they molt five times in total, becoming sixth-instar larvae before they begin spinning silk and making cocoons.

3. Sixth-instar larvae need two days and two nights to form one cocoon, and the silk used to make the cocoon can actually be drawn out to a length of 1.5 kilometers! Inside the cocoon, the silkworm undergoes its final molt and becomes a pupa. After about ten days, it emerges as a silkworm moth and breaks out of the cocoon. After emerging from the cocoon, the female moth emits a scent from the tip of her abdomen to lure the male moth to mate. After mating, the male moth dies immediately, and the female moth takes about one night to lay about 500 eggs, after which she also slowly dies.

II. What else can silkworm babies eat besides mulberry leaves?

Silkworm babies can eat many kinds of food. Besides mulberry leaves, there are also leaves of silkworm thorn, elm, fig, broadleaf willow, dandelion, lettuce, romaine lettuce, salsify, and so on, no fewer than twenty kinds; however, silkworm babies love eating mulberry leaves the most. This is because silkworms spend the most time living on mulberry leaves as food, and generation after generation they reproduced on mulberry trees, gradually forming the characteristic of being most accustomed to eating mulberry leaves, which even became hereditary. A chemist once analyzed the scent in mulberry leaves. After distilling mulberry leaves at a high temperature of 132-157 degrees C, he obtained an oily substance in a test tube, like vinyl alcohol and vinyl aldehyde. This substance is volatile, much like the scent of mint, and when dropped on paper, silkworms 30 cm away can smell it. After smelling this scent, silkworms quickly crawl over. It can be seen that this is the signal scent most familiar to silkworms. Silkworms rely on their olfactory and gustatory organs to recognize the scent of mulberry leaves. If these olfactory and gustatory organs are damaged, they cannot distinguish the scent of mulberry leaves, and then they are no longer picky and can casually eat some other leaves.

In recent years, in the progress of research on artificial feed for silkworms, people have basically identified the types of nutrients necessary for silkworm growth and their minimum required amounts. Only by eating mulberry leaves can silkworm babies grow and develop healthily and smoothly complete their alternation of generations.