Silkworms are a species of insect (Bombyx Mori) that is domesticated, meaning they are dependent on humans for survival.
Silkworms live happily in the breeding box you provide for them and do not attempt to escape, they lack fear of predators and are used to being handled by humans.
The availability of Silkworm Chow makes this a project that can be undertaken at any time of the year.
Silkworms grow and cocoon in around 6-8 weeks. In the hotter months of the year the larval (worm stage) can be as short as 21 days. Time from hatching to cocooning (the larval/worm stage) depends on ambient temperature and food availability. If worms are kept at a even and adequate temperature and have constant access to food they will grow fast. Silkworms remain in their cocoons for approximately 10 days before emerging as moths.
The Silkworm moths generally do not fly and will usually stay in the breeding box (Male moths may fly briefly or leave the breeding container in search of a female). The Silkworms moths live for approximately 3 days, but can survive up to two weeks.
The empty cocoons when prepared correctly, make glossy white silk. This is excellent for Art/Textile projects where students discover the transformation from cocoon to silk. It is also fun to prepare!
Silkworms hatch naturally in Australia from Early July depending on the region you live in. Whilst they usually (amazingly) coincide their hatching with the first emergence of leaves on the local mulberry trees, occasionally they can emerge too early due to any unusual temperature fluctuations. Because of this, placing them in cold storage is the best way to ensure you do not loose any hatchlings before leaves are available.
Silkworm hatchlings do not all emerge at the same time. A batch of eggs can hatch continuously over a 6 week (or longer) period which is another good reason to refrigerate eggs for the last few months, giving them a even temperature and so helping them to hatch within the same one week period.
The first hatchlings are dark and furry looking! this is the first ‘INSTAR’, there are 5 INSTARS separated by four MOULTS of the silkworms skin.
After the 4th and last MOULT and the last period of growth in which the silkworm devours over half of the mulberry leaves it will consume in its lifetime, it begins to spin a silk cocoon around itself. This can take over 48 hours to complete! The silkworm uses one continuous strand up to 900 meters long!
Silkworms do unusual things like spin a cocoon with a friend, or get confused and spin a flat mat underneath themselves, but most of the worms will create for themselves a perfect ovate cocoon.
Inside the cocoon the silkworm MOULTS for the last time when it becomes a PUPA.
This is the stage in the silkworm industry that the cocoons are baked or boiled to kill the pupa, then each cocoon is ‘REELED’. This is when one continuous strand of silk is unwound from each cocoon, either by hand or by a machine. 6-8 of these strands are twisted together to create one thread of silk. Often the cooked PUPAS are eaten and in some countries are a valuable source of protein.
AT PEACEFUL SILKWORMS EVERY MOTH IS ALLOWED TO HATCH FROM ITS COCOON.
Each Silkworm stays in its cocoon for approximately 10 days then hatches inside the cocoon from its pupa skin, the moth then secretes a PROTEIN SALIVA that ‘melts’ open the SERICIN of the cocoon (the yellow ‘wormspit’ that holds the silk strands together) so it can push itself out.
Once out the moth dries its wings and finds a mate (or vice-versa as is often the case!), the females are larger than the males as their abdomens are full of unfertilized eggs.
Females have enlarged abdomens and appear to drag their abdomens along when they walk. The males are smaller, flutter a lot and bend the end of their abdomens around continuously. Male moths have small narrow abdomens but sometimes their abdomens can be large like the females. The fluttering behavior of males is the best way to identify them. Female behavior is to walk slowly and sit in one place with the abdomen raised and yellow genitalia visible (when waiting for a mate). females sometimes show a ‘flutter’ behavior usually displayed whilst sitting in one place. The flutter is generally rhythmic with both wings in sync. Often all the females will display this behavior at the same time.
Soon after mating the female lays her eggs – between 200 – 500 individual eggs. As the moths do not eat or drink they die naturally soon after laying their eggs, the males may mate with more than one female before they die.
The eggs remain in a state called DIAPAUSE until they have been through a period of cold (winter). When the temperature rises in spring they begin to develop and hatch ready to eat the first tender shoots on the Mulberry trees.
All BOMBYX MORI Silkworms are DOMESTICATED and cannot survive on their own in the wild. They can not hang on strongly and will blow or fall out of trees. As they cannot travel far they will starve to death on the ground or be eaten by predators, so please do not set your silkworms ‘free’. The moths have reduced mouth parts and cannot eat or fly and both worms and moths lack fear of predators.
Some species of silkworms harvested for their silk are still wild. Unfortunately these are not present in Australia and Customs regulations prevent them being imported.