Silkworms are a great species for studying the life-cycle of a caterpillar. This can be done in your home or classroom with a few simple items and a steady supply of mulberry leaves. They are not native to Australia so you will not find them in the wild and you should not release them into the wild when you're finished with them. You can source your eggs from pet shops or local breeders.
From larva to moth via silk coccoon.
In their own country, silkworms would live on mulberry trees as this is their only source of food and their waste would drop to the ground. In captivity, you need to provide a clean and comfortable alternative. A shoebox with plastic wrap is an easy option. Keep the box at room temperature but out of direct sunlight. Puncture the plastic wrap with small air holes, but make sure they're not big enough for your silkworms to escape! You may need to place the shoebox above a moat of water to stop ants getting in!
About six weeks after the eggs have hatched they will start to spin coccoons. At this stage you need to add some sticks, curved bark or cardboard rolls to the shoebox so the caterpillars have edges to attach their silk to.
The caterpillars feed mainly on mulberry leaves. If you obtain eggs before the mulberry trees have developed leaves then you can put the eggs "on hold" in the fridge. If they hatch anyway, you can feed them on carefully washed lettuce leaves.
When your caterpillars are young, tear the mulberry leaves into smaller pieces so there are lots of edges for them to eat along.
You will need to clean the box out every day as the silkworms eat a lot of leaves and that creates a lot of caterpillar poo! As they grow larger they will moult so old skins need to be thrown out too. The bigger the caterpillars get, the more leaves they eat. Eventually, you will need to feed them every few hours. But you can plan ahead and pick lots of mulberry leaves which last several days in a plastic bag in the fridge.
To clean the box without damaging the delicate caterpillars pick up the leaves they are on rather than picking up the caterpillars themselves.
About six weeks (or up to 47 days) after hatching from eggs the caterpillars start to spin their coccoons. These are made from one long strand of silk about 800-1200 metres long and this process can take 3 to 6 days.
In this picture you can still make out some of the features of the caterpillar as it spins its coccoon within the silk anchors.
Parts of the caterpillar
Silworms have a head, a thorax and an abdomen. The head has simple eyes and tiny feelers. The silk is made by two glands near the mouth. The thorax has three segments and each of these has a pair of legs. Along the abdomen there are false legs that silkworms use for gripping and balancing. The whole abdomen has 10 segments.
The moth will hatch about 15 days after the coccoon is finished. The moths cannot eat or fly and they only live for a few days which is enough time to mate and lay eggs so that the cycle can start all over again.
Activity - Watch an online slideshow about silkworms. What extra facts does it contain?
Activity - Draw and label a silkworm or draw and label your own life cycle of a silkworm.