兒子開始養(yǎng)蠶寶寶了，做個思維導(dǎo)圖講一下蠶。
蠶的幾個階段的英文介紹
Where does silk come from?
Silk is an expensive and beautiful piece of fabric that used to be worn by only kings and royalty in the past. It comes from the silkworm. The lifecycle of a crawling worm into a moth goes through several stages.
5 Important Stages in the Life Cycle of a Silkworm
Stage 1: The Egg
This is the first stage of a silkworm’s life cycle. The female moth lays eggs which are the size of a small ink dots! The female can lay more than 350 eggs at a time. These eggs remain dormant till springtime when the warmth in the air arouses them to hatch. This happens once a year. But due to human intervention the breeding of silkworm and hatching of eggs takes place at least thrice a year.
Stage 2: Larvae
When the eggs crack there emerges a hairy silkworm. This larva stage is the one where growth takes place. Upon hatching, a silkworm is 1/8th of an inch. They feed on tender mulberry leaves. They consume large amount of these leaves for 20 to 30 days and go through four stages of molt or skin changes. The first molt is when the silkworm sheds all its hair and attains a smooth skin.
Stage 3: Cocoon
At this stage the silkworm spins a protective cocoon around itself. It is made by a single thread of silk and it the size of a small cotton ball. This, it does to protect itself from predators. This is the stage where the second molt takes place when the lava turns into a pupa inside the cocoon.
Stage 4: Pupa
This stage is the motionless stage just before adulthood. It is at this stage when people take the cocoon and plunge it into boiling water to kill the pupa and unwind the silk thread. But if they don’t the pupa rests peacefully for 2-3 weeks after which it metamorphoses into an adult moth.
Stage 5: Adult moth
The pupa changes itself into a beautiful adult moth. These moths are flightless and do not have a mouth so they are unable to consume food. Once the adult moth comes out its sole purpose is to find a mate. Within 24 hours of mating a male moth dies while the female lays eggs and then even she dies. Thus the lifecycle of a silkworm begins again.
4 Interesting Facts about Silkworm
1. Normally silkworms reproduce only once a year but in countries like India and China they can do so round the year because of the weather.
2. Silkworms is the term used for the worms called Bombyx Mori.
3. The salivary gland of the silkworm larvae produces the silk thread for the cocoon.
4. One cocoon will contain raw silk thread of 300 to 900 meters in length.