The life cycle stages of the silkworm moth Bombyx mori

Phylum, Arthropoda; Class, Insecta; Order, Lepidoptera

The silk worm larval life is divided into five instars, separated by four molts. Four distinct stages of development complete one generation of the species;
ova, larvae, pupa and imago.
The common name silkworm or caterpillar   is used for the larvae of the moth  Bombyx mori.
After hatching from the egg, larvae go through four molts as they grow. During each molt, the old skin is cast off and a new, larger one is produced. The silkworm's larval life is divided into five instars, separated by four molts.
silkworm.moth.and.eggs..jpg (180024 bytes) On the photo left the female silk moth can be seen partly upper left and male silk moth is in the middle.  The size diference is easy to see.  The fresh pale yellow eggs will turn to gray.


STAGE 1 - OVA: Incubation 10-14 days
Newly laid eggs are a creamy yellow, after a few days the fertile live eggs will be gray.  Keep the eggs cool.  In the winter this is easy, but the eggs must be placed in the fridge as soon as it starts to warm up for spring.   Do not freeze the eggs, keep them in the warmest part of the fridge..
The silkworm eggs will hatch 2 weeks after you remove them from the fridge. 


STAGE 2 - LARVA: 27 DAYS (5 instars)

After four days the first molt will occur. 

After hatching the tiny larvae grow the best if they are fed on the new soft leaves of the mulberry tree.  Switch over to larger leaves as they grow.  The silkworms(larvae) do nothing but eat.  Keep them in a flat open box. They will not crawl away. Simply place leaves in the container and place the silkworms on the leaves. Keep them at room temperature, but not in direct sunlight.

If you have got many silkworms then it is best to make wooden frames with a fine mesh grid at the bottom so that the worm droppings and fine pieces of leaves can fall through.  Stand the frame in a tray to catch the debris.    Everything must be kept clean.  Transfer the tiny silkworms using a small paint brush the first few days, older larvae can be gently picked up with your hands onto a clean tray. Give fresh leaves and remove half eaten leaves from the day before, every day. (34866 bytes)



The silkworm will spin a silk cocoon  as protection for the pupa. Cocoons are shades of white, cream and yellow. The glistening shine of the silk gives an impression of silver and shades of gold. After a final molt inside the cocoon, the larva change into the brown pupa. Further changes inside the pupa result in an emerging moth (55751 bytes)


STAGE 4 - IMAGO: 5 - 7 DAYS 

An adult silk moth emerges from the cocoon about two weeks after completion.  This is the adult stage of the silkworm, Bombyx mori. The body of the moth is covered in short fine hair and wings are creamy white with faint brown lines.  Moths can not fly or consume nutrition. Females are larger and less active than the males. Male moths move about beating their wings seeking females.

If adults copulate in captivity, the female will lay eggs within 24 hours. The female usually lies the eggs on the vertical side of the box or tray.  Cover the whole surface with sheets of paper making it easier to remove the eggs for storage.
photo of the moths click here


Raising the silkworms Glossary

How to spin the hearts

Silkthread for spinning
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