The life cycle of a Silk Worm
The silkworm is the larva stage of the silk moth's life cycle. Moths lay eggs which develop into the silkworm larvae, grub or caterpillar (commonly called silkworms). They eat for 20-30 days, consuming large amounts of mulberry leaves, and molt through four changes of skin or 'instars'. Silkworms (at all four instars) are a very nutritious live feeder for reptile pet lizards and semi-aquatic pets too.
The silkworm larvae (caterpillar) spins a cocoon for protection, to permit the development of the pupa or chrysalis. which takes about three days to be fully completed, and is a similar size to a peanut shell.
The chrysalis emerges from the cocoon as a moth. In cultivated, commercially viable, silk the grub is terminated while still inside the cocoon so that the long filaments are maintained and preserved for the production of silk.
The colour of the silk filament can be determined by the diet of the larvae and seasonal influences. Mulberry leaves produce the preferred lighter coloured cocoons, but in the wild silk worms will eat other plants as well producing a variety of colours, as shown here at top
The moths mate and the females lay 300, to more than 350 eggs, then die.
In the wild this cycle occurs once a year, but under controlled scientific breeding it can occur up to three times in one year.The Latin (scientific) name for the silkworm is Bombyx mori, which means "silkworm of the black mulberry tree". Silkworms are caterpillars that spin a silk cocoon and change into silkworm moths, while inside their cocoon, emerging to mate and lay eggs.
After hatching from an egg the worm takes about one month to grow large enough to spin the silk. These horworms then spend about three weeks in the cocoon to emerge as a moth, to mate and lay their eggs. The eggs hatch into worms in a few weeks, and then the cycle repeats itself.
Silkworms go through four stages of development, as do most insects: egg, larva, pupa and adult: the adult (imago) stage is the silkworm moth. The larva is the silkworm caterpillar. Since the silkworms (that is the larvae stage) grow so much they must shed their skin four times while growing. These stages-within-a-stage are called instars. Silkworms only eat fresh mulberry leaves. Silkworms do 85% of their eating during their 5th instar as it reaches around 2-3/4" in lenght; the larva has increased its size 10,000 times, since birth, and its silk glands now make up 25% of its body weight, ready to spin its silk cocoon.
The first chart (below left) shows the entire life-cycle (clockwise). The second photo shows a silkworm caterpillar in the 5th instar, the pupa (brown), the silk cocoon (yellow), and finally the silk moth. The third photo shows 3 silkworms in their 4th instar stage (about 2" long). The last photo (below right) shows the silk moth, which does not eat or defecate, and only lives for a couple of days to lay her eggs and then dies. The entire life-cycle is between five and a half weeks to seven weeks, depending on climate conditions.
Silkworms (in the second to the fifth intars) make excellent live feeders for your exotic omnivorous pets as they are high in protein and low in fat, have a balanced one-to-one Calcium-to-Phosphorous ratio, and are the only larvae producing the enzyme 'serrapeptase' which is an excellent anti-inflammatory and pain reliever, aids calcium absorption and also fights arterial plaque.