Empty cocoons: rough silk fibers for spinning
Silkworms are caterpillars of several species found whithin the Lepidoptera super family Bombycoidea, namely whithin the Saturniidae and Bombycidae families. Their name derives from the ability to produce silk, which is spun to build a cocoon around the animal. The cocoon protects the pupae from environmental injuries and guarantees a safer environment for the pupae to develop.
Normally, Lepidoptera breeders do not consider empty cocoons as a valuable resource for spinning and craft art in general. Cocoons are normally just thrown away after adult emergence. Sadly, we did so for a while too until recently, after being in contact with our friend Ellen Hengeveld from the Netherlands. She showed us how amateur Lepidoptera breeding can meet homemade spinning.
In this brief article we want to explain the interesting world behind those empty cocoons, giving an overview on the silk production from silk moths.
Different moth species, different silk
The silk which is normally used in the textile industry does not came from wild Bombycoidea species but is produced out of domesticated silk moth species. Those species have been reared for centuries in captivity and selected for the quality of the silk they produce. The major part of silk farming is done with Bombix morii, which is is the closest relative of Bombix mandarina, the wild silk moth. Its preferred food is white muldberry leaves, though they may eat other mulberry species.
Another domesticated species, which is intensively reared, although to a very less extent compared to Bombix morii, is Samia ricini, the Eri silk moth. Samia ricini is though to be a multi hybrid between east-Asia wild Samia species. Many silk farms in Asia regularly cross Samia ricini adults with other wild Samia sp., this is done in order to avoid extreme genetic drift in their captive population, thus reduction in quantity and quality of silk produced. Samia ricini main host plant is Ricinus communis, but can be also fed on Ailanthus altissima and Ligustrum sp.
We do sell Samia ricini eggs in our shop, funny and easy species to rear and breed. It also produces quality white silk, that can be used to various purposes, from hobby rearing to silk production.
Many other Bombycoidea species are reared all around the world, those species are generally not domesticated and their blood is often refreshed with animals from the wild. In this case we talk about “wild silk”. Examples of such species are: Antheraea mylitta in India, Cricula trifenestrata in Indonesia (shown in picture above) and Anthereae yamamay in Japan. If you google it, you will find out that A. yamamay has inspired the name of a famous clothes shop.
What does cruelty free silk means
In the traditional silk production process, animals are boiled after they have spun the cocoons. This practice has recently raised more and more controversy, resulting in a lower diffusion of silk-made products. Such controversy has shaded the value of silk as a low cost, low maintenance, eco friendly alternative for many fibers. There is a call for alternatives to such procedures, which terminate with the death of the animal.
As we reared many Samia ricini in the past years, we have collected their cocoons after emergence, and we are currently testing them for silk fibers production. This way we may show that upon hatching, the animal is not compromising silk quality, that can anyway be used for spinning purposes.
Thus, in our facilities, animals hatch from the cocoons. They aren’t killed but paired to produce new offspring. This is the reason why you will find the empty pupae inside the cocoon, this is the clear sign the the adult has properly hatched.
Unfortunately, if animals are free to hatch, some cocoons might be dirty because of meconium, which is the earliest stool of the adult after emergence. Do not worry, meconium is easily cleaned with water. Some of the cocoons may also be cut opened but, according to our tests, this seems still good for spinning fibers.
Here you can find our ad for 120 grams of rough Samia ricini silk.
cover image courtesy of Ellen Hengeveld