How do silkworms become silkworm moths? How many days does it take for the eggs to hatch? How many times do you have to shed your skin in your life? Four growth processes of silkworm babies

Bombyx mori, also known as silkworm, silkworm, is a common economic insect in southwest China, Jiangsu and Zhejiang, Anhui and other places, because it can spin silk and can be made into a variety of silk fabrics, how does the silkworm become a silkworm moth? How many days does it take for the eggs to hatch? How many times do you have to shed your skin in your life? The four growth processes of silkworm babies.

First, the four growth processes in which a silkworm becomes a silkworm moth:

The first process: Silkworm eggs

A female moth can lay about 400 million 500 silkworm eggs at a time. It is yellow or light yellow when it is first laid. After 1 to 2 days, it changes to red bean or light red bean, and after 3 to 4 days, it changes to purple or grayish green. Its outer layer is a hard egg shell, inside is serosa and yolk. The embryo in the fertilized egg continuously absorbs nutrients during development. The silkworm egg looks like Ganoderma lucidum, which is generally about 1 mm wide. It is about 0.5 mm thick and gradually develops into an ant silkworm when it reaches a certain temperature.

The second process: ant silkworm

The ant silkworm is the hatched silkworm egg, the body is very small, the color is black or brown, and many fine hairs, looks a bit like ants, so it is called ant silkworm. The ant silkworm is about 2 mm long and 0.5 mm wide. After climbing out, it will eat tender mulberry leaves after 2-3 hours.

In general, when the hatching temperature reaches 20-30 ℃, the eggs will hatch within 9-11 days, especially at 22-25.5 ℃. For those who have been promoted, it will take 2 to 9 days. In spring, if the natural temperature is above 12 ℃, it can hatch in 22 to 27 days, if the diapause period, when the temperature reaches 25 to 30 ℃, it will take 30 to 100 days. If it is higher than the maximum temperature, it will affect the hatching rate.

The third process: mature silkworm

At the end of the fifth instar, the baby silkworm gradually showed the characteristics of maturity and mouth spitting silk wisps. First, the excreted feces changed from dark green to leaf green, from hard to soft, and showed a decline in mulberry intake and loss of appetite. The chest is transparent, the front digestive tube is empty and other obvious symptoms, and then completely stop eating, swinging up and down to find cocoon sites, silkworm head and chest raised, such silkworms are called mature silkworms.

The fourth process: cocoon

After a certain period of time, mature silkworms begin to spin and stop feeding. At this time, silkworm farmers put them in special containers or pots in order to spin cocoons. Cocoons are white, yellow, light green, flesh red and other colors, about 3 cm long, 1.7 cm 2.1 cm in diameter, white surface, irregular wrinkles, and attached silk, fluffy, the inner wall of the silk is very regular, light and tough, not easy to tear, unfeathered cocoon, there is a yellowish brown silkworm pupa and light brown, wrinkled silkworm skin taken off before becoming a pupa.

The four processes of silkworm cocooning:

The main results are as follows: (1) the mature silkworm first spits out the silk, binds it to the silkworm, and then spins it to connect the surrounding twigs to form a cocoon bracket, that is, the cocoon net. The cocoon net does not have a cocoon shape, but some soft and messy cocoon silk layers, which can be used as a support for cocooning.

(2) after forming the cocoon net, continue to spit out the messy silk ring, thicken the inner layer of the cocoon net, and then spin silk in the S-shaped way, and begin to appear the outline of the cocoon, which is called cocoon clothing. The silk fiber of cocoon clothing is fine and brittle, the arrangement is extremely irregular, and the sericin content is also high.

(3) after the cocoon coat was formed, the cocoon cavity gradually became smaller, and the front and back ends of the silkworm body bent to the back into a "C" shape. The silkworm continued to spit out cocoon silk, and the spinning mode changed from S-shaped to ∞-shaped, which began the process of cocooning layer.

(4) when the silkworm's body is greatly reduced due to a large amount of silk spinning, the swinging speed of the head and chest slows down, and there is no certain rhythm, silk spinning begins to appear messy, forming a loose and soft cocoon silk layer, which is called pupa lining.

The fifth process: Silkworm moth

The silkworm moth is shaped like a butterfly and is covered with white scaly hair, but because the two pairs of wings are small, it has lost its ability to fly. Generally, after mating for 3 to 4 hours, the female moth can lay fertilized eggs, and the male dies immediately after mating. The female moth can lay about 500 eggs in about one night, and then slowly die.

Second, why sleep when growing up? Molting?

1. Why should you shed your skin?

In the process of growth and development, silkworms shed their skin once, and during the molting period, they do not eat anything and molt safely in the form of sleep. after a peeling, they become the second instar larvae, and even if the peeling is increased by one year, the larvae have to peel four times to become the fifth instar larvae, and then eat mulberry leaves for 8 days to become mature silkworms.

2. Why sleep?

The silkworm goes through four times of peeling in the process of growth, and before each peeling, it has to go to sleep, the purpose is to prepare for molting, and the treatment of sleep includes three processes: pre-sleep treatment, sleep protection and silkworm treatment.

(1) pre-sleep treatment: that is, when the silkworm enters the period of starvation, it should add sleep and feed 1-2 leaves, which is about to sleep and remove, so that the sleeping silkworm has a dry silkworm seat. The amount of mulberry given before bedtime is gradually reduced, which is not only not a waste of mulberry leaves, but also conducive to silkworm seat leveling and netting. After most silkworms sleep, the 1st and 3rd instar silkworms use 7 parts of fresh lime powder and 3 parts of coke bran, and the 4th and 5th instar silkworms all use fresh lime powder to stop mulberry, then Tiqing net moves it to another silkworm plaque, and feed high-quality mulberry leaves for its growth and development, which can catch up with the development of a large number of silkworms after 3-4 days. Pay attention to the observation of green-headed silkworms and eliminate the weak and diseased silkworms in time. Green-headed silkworms should be reared alone, not mixed with a large number of silkworms to prevent silkworm disease transmission.

(2) Protection of dormancy period: the length of dormancy period of silkworm was obviously affected by temperature. According to the normal temperature protection, the dormancy period of 1st instar, 2nd instar, 3rd instar and 4th instar were about 22 hours, 18 hours, 20 hours, 24 hours and 44 hours respectively. The temperature during the dormancy period is about 1 ℃ lower than that of normal feeding, and the indoor humidity should be observed at all times in the early stage of silkworm dormancy (before peeling to rates feeding). Generally, the difference between dry and wet is about 2 ℃, and a little higher humidity is beneficial to the molting of silkworm. The sleeping environment should be quiet, the light should be dark, the air should be fresh, and the strong wind should not blow directly.

(3) after the silkworm treatment, the beige head of the silkworm after molting is the suitable period for rate feeding, which is beneficial to the development of silkworm, but has no adverse effect on silkworm physique and cocoon yield. Spring silkworm, mid-late autumn silkworm molting 90% 95% rate feeding, summer silkworm, early autumn silkworm temperature is higher, silkworm molting 85% 90% rate feeding. Use silkworm seat net or disease prevention No. 1 or anti-stiffness agent to disinfect silkworm body and silkworm seat before feeding, in order to kill germs. Feed the second leaf after the rate to remove. If the silkworm head is more crowded, the silkworm is not in batches before sleep, the silkworm can be divided into two batches, that is, after the silkworm body and silkworm seat are disinfected, add the net to the mulberry, pay attention to observe that the silkworm crawls half of the net and lift the silkworm net after several hours, wait for the dormant silkworms to shed their skin for the second time.

There are two methods of feeding and screening in batches: one is to add two silkworm nets horizontally to each silkworm plaque (each accounts for half of the silkworm seat area), and each silkworm net is divided into two silkworms. Another way: each silkworm plaque first add a silkworm net, the silkworm net area is slightly larger than the silkworm seat, when the silkworm climbs to about half of the silkworm net, that is, the silkworm net is removed, and the other half of the silkworm is renetted to mulberry for removal. In this way, the time of seat expansion can be saved, and the silkworm body will not be injured. The edible leaves should be ripe and tender, and the amount of leaves should be less to prevent waste. With the increase of the amount of mulberry eaten, the amount of leaf feeding also increased.

Third, why cocoon?

1. Why can you form a cocoon?

The silkworm cocooning is related to the silk gland organs in the silkworm body. from the growth process of the silkworm, in the larval stage, the silkworm will digest and absorb the nutrients in the mulberry leaves after eating a large number of mulberry leaves, especially the various amino acids in the mulberry leaves will be absorbed and stored by the silk glands in the silkworm body. With the increase of silkworm age, the silk gland also increased, especially at the fifth age. From the appearance before spinning and cocooning, we can see that the chest of the silkworm is slightly transparent, which is due to the accumulation of a large amount of protein in the silk gland.

2. Why cocoon?

From the physiological point of view of the silkworm, because the protein that makes up the silk gland is composed of amino acids, if there are too many amino acids in the silkworm body, the silkworm will be poisoned, so the silkworm needs to remove amino acids to achieve the purpose of detoxification. Under natural conditions, the silkworm, as a completely abnormal insect, is very fragile at every stage of life, especially in the silkworm pupa stage, which will stop feeding, lose the ability to act, and be easily hurt by natural enemies. The silkworm evolves the behavior of spinning and cocooning, enclosing itself in a dense cocoon shell, so that it can not only avoid natural enemies to protect itself, but also safely turn into a silkworm pupa in the cocoon, and transform the organs in the silkworm pupa into the shape of a silkworm moth. and finally feathered into a silkworm moth.

3. What to do after cocooning?

After cocooning, the silkworm will molt and pupate in the cocoon, break the cocoon in 8 to 10 days, and die naturally in a week after mating and laying eggs. Therefore, after cocooning, the silkworm can lay a piece of white paper at the bottom of the clean and odorless carton, and it is also covered with a layer of white paper (don't stick to death). Put the cocoon in the box, the cocoon-breaking moth will mate, and the female moth lays eggs on the paper. In silk production, if the pupa is allowed to metamorphose into an adult and naturally dissolve and drill out of the cocoon, the silk thread will become shorter and cannot be used for spinning and weaving silk, so the cocoon should be put into boiling water before it is broken to kill the pupa and make the cocoon easy to disassemble.