Editing Bombyx mori (section)

=== Pupae (cocoon) ===
After they have molted four times, their bodies become slightly yellow, and the skin becomes tighter. The larvae then prepare to enter the pupal phase of their life cycle, and enclose themselves in a cocoon made up of raw silk produced by the [[salivary gland]]s. The final molt from larva to pupa takes place within the cocoon, which provides a layer of protection during the vulnerable, almost motionless pupal state. Many other [[Lepidoptera]] produce cocoons, but only a few&nbsp;— the Bombycidae, in particular the genus ''Bombyx'', and the [[Saturniidae]], in particular the genus ''[[Antheraea]]''&nbsp;— have been exploited for fabric production.

The cocoon is made of a thread of raw silk from {{convert|300|to about|900|m|ft|sigfig=1}} long. The fibers are fine and lustrous, about 10&nbsp;μm in diameter. The number of cocoons required to produce a final yield of silk is approximately {{convert|2000-3000|/lb|/kg|sigfig=1|order=flip}}; at least {{convert|70|e6lb|e6kg|order=flip|abbr=off}} of raw silk are produced each year, requiring nearly 10 billion cocoons.<ref>{{cite web|url=http://faostat.fao.org/site/603/DesktopDefault.aspx?PageID=603#ancor|title=faostat.fao.org}}</ref>{{Better source needed|reason=FAO link is vague|date=July 2023}}

If the animal survives through the pupal phase of its life cycle, it releases [[Protease|proteolytic enzymes]] to make a hole in the cocoon so it can emerge as an adult moth. These enzymes are destructive to the silk and can cause the silk fibers to break down from over a mile in length to segments of random length, which reduces the value of the silk [[Yarn|threads]], although these damaged silk cocoons are still used as "stuffing" available in China and elsewhere in the production of [[duvet]]s, jackets, and other purposes. To prevent this, silkworm cocoons are boiled in water. The heat kills the silkworms, and the water makes the cocoons easier to unravel. Often, the silkworm is eaten.

As the process of harvesting the silk from the cocoon kills the pupa, sericulture has been criticized by animal welfare and rights activists. [[Mahatma Gandhi]] was critical of silk production based on the ''[[ahimsa]]'' philosophy "not to hurt any living thing". This led to Gandhi's promotion of cotton spinning machines, an example of which can be seen at the Gandhi Institute,<ref>{{cite book |editor=S. Radhakrishnan |title=Mahatma Gandhi: 100 Years |date=1968-01-01 |isbn=071892035X |page=349 |url=https://books.google.com/books?id=LGVuAAAAMAA |accessdate=2025-04-18}}</ref> and an extension of this principle has led to the modern production practice known as [[Ahimsa silk]], which is [[wild silk]] (from wild and semiwild silk moths) made from the cocoons of moths that are allowed to emerge before the silk is harvested.