Features, characteristics, reproduction and why does a person need a silkworm? Silkworm (lat. Bombyx mori) - the only domesticated insect Where silkworm lives

People know a lot about the merits of silk, but few people are familiar with the "creator" who gave the world this miracle. Meet the silk caterpillar. For 5,000 years, this small, humble insect has been spinning silk thread.

Silkworms eat the leaves of mulberry (mulberry) trees. Hence the name silkworm.

These are very voracious creatures, they can eat for days without a break. That is why hectares of mulberry trees are specially planted for them.

Like any butterfly, the silkworm goes through four life stages.

• Larva.
• Caterpillar.
• A chrysalis in a silk cocoon.
• Butterfly.

As soon as the head of the caterpillar darkens, the lenok process will begin. Usually the insect sheds its skin four times, the body becomes yellow, the skin acquires density. So the caterpillar moves to a new stage, becomes a chrysalis, which is in a silk cocoon. AT natural conditions the butterfly gnaws a hole in the cocoon and shaves itself out of it. But in sericulture, the process proceeds according to a different scenario. Manufacturers do not allow silkworm cocoons to "ripen" to the last stage. Within two hours under the influence of high temperature ( 100 degrees), the caterpillar then dies.

Appearance of a wild silkworm

Butterfly with big wings. Domesticated silkworms are not very attractive (the color is white with dirty spots). It is radically different from the "home relatives" is a very beautiful butterfly with bright large wings. Until now, scientists cannot classify this species, where and when it appeared.

In modern sericulture, hybrid individuals are used.

1. Monovoltine, produces offspring once a year.
2. Polyvoltine, gives offspring several times a year.

Silkworm cannot live without human care, it is not capable of surviving in the wild. The silkworm caterpillar is not able to get food on its own, even if it is very hungry, it is the only Butterfly that cannot fly, which means that it is not capable of finishing food on its own.

Useful properties of silk thread

The productive ability of the silkworm is simply unique, in just a month it is able to increase its weight ten thousand times. At the same time, the caterpillar manages to lose “extra pounds” four times within a month.

It would take a ton of mulberry leaves to feed thirty thousand caterpillars, enough for the insects to weave five kilograms of silk thread. The usual production rate of five thousand caterpillars yields one kilogram of silk thread.

One silk cocoon gives 90 grams natural fabric. The length of one of the threads of a silk cocoon can exceed 1 km. Now imagine how much work a silkworm needs to work on, if on average 1,500 cocoons are spent on one silk dress.

Silkworm saliva contains sericin, a substance that protects silk from pests such as moths and mites. The caterpillar secretes a viscous substance of sloping origin (silk glue) from which it spins a silk thread. Despite the fact that most of this substance is lost during the manufacture of silk fabric, even the little that remains in the silk fibers can save the fabric from the appearance of dust mites.


Thanks to serecin, silk has hypoallergenic properties. Due to its elasticity and incredible strength, silk thread is used in surgery for suturing. Silk is used in aviation; parachutes and balloon shells are sewn from silk fabric.

Silkworms and cosmetics

Interesting fact. Few people know that a silk cocoon is an invaluable product; it is not destroyed even after all silk threads are removed. Empty cocoons are used in cosmetology. Masks and lotions are prepared from them not only in professional circles, but also at home.

silkworm gourmet food

Few people know about the nutritional properties of the silk caterpillar. it ideal protein product, it is widely used in Asian cuisine. In China, the larvae are steamed and grilled, seasoned, usually huge amount spices, you won’t even understand what “lies on a plate”.


In Korea, they eat half-cooked silkworms, for which they are lightly fried. This is a good source of protein.

Dried caterpillars are commonly used in traditional Chinese and Tibetan medicine. The most interesting thing is that mold fungi are added to the “medicine”. Here is a useful silkworm.

What do good intentions lead to?

Few people know that gypsy moth, which is the main pest of the US forestry industry, spread as a result of an unsuccessful experiment. As they say, I wanted the best, but the following came out.

The silkworm is represented by monovoltine (give one generation a year), bivoltine (give two generations a year) and polyvoltine (give several generations a year) breeds.

Egg

After mating, the female lays eggs (500 to 700 on average), the so-called grena. Grena has an oval (elliptical) shape, flattened laterally, somewhat thicker at one pole; soon after its deposition, one impression appears on both flattened sides. At the thinner pole there is a rather significant depression, in the middle of which there is a tubercle, and in the center of it there is a hole - a micropyle, designed for the passage of the seed thread. The size of grena is about 1 mm long and 0.5 mm wide, but it varies considerably between breeds. In general, breeds of European, Asia Minor, Central Asian and Persian give a larger gren than Chinese and Japanese. Egg laying can last up to three days. Diapause in the silkworm falls on the egg stage. Diapausing eggs develop in the spring of the following year, while non-diapausing eggs develop the same year.

Caterpillar

A caterpillar comes out of the egg (so-called silkworm), which grows rapidly and molts four times. After the caterpillar has gone through four molts, its body becomes slightly yellow. The caterpillar develops within 26-32 days. The duration of development depends on the temperature and humidity of the air, the quantity and quality of food, etc. The caterpillar feeds exclusively on mulberry leaves (mulberry tree). Therefore, the spread of sericulture is associated with the places where this tree grows.

While pupating, the caterpillar weaves a cocoon, the shell of which consists of a continuous silk thread ranging in length from 300-900 meters to 1500 m in the largest cocoons. In the cocoon, the caterpillar turns into a chrysalis. The color of the cocoon can be different: pinkish, greenish, yellow, etc. But for the needs of industry, only silkworm breeds with white cocoons are currently bred.

The release of butterflies from cocoons usually occurs on the 15-18th day after pupation. But the silkworm is not allowed to survive to this stage - the cocoons are kept for 2-2.5 hours at a temperature of about 100 ° C, which kills the pupa and simplifies the unwinding of the cocoon.

The history of breeding this butterfly, belonging to the family of real silkworms (Bombycidae), is associated with ancient China, a country long years who kept the secret of making an amazing fabric - silk. In ancient Chinese manuscripts, the silkworm was first mentioned in 2600 BC, and during archaeological excavations in the southwest of Shanxi province, silkworm cocoons dating back to 2000 BC were found. The Chinese knew how to keep their secrets - any attempt to take out butterflies, caterpillars or silkworm eggs was punishable by death.

But all secrets will eventually be revealed. This is what happened with silk production. First, some selfless Chinese princess in the 4th century. AD, having married the king of small Bukhara, she brought him a gift of silkworm eggs, hiding them in her hair. About 200 years later, in 552, two monks came to the emperor of Byzantium, Justinian, who offered to deliver silkworm eggs from distant China for a good reward. Justinian agreed. The monks went to dangerous journey and returned the same year, bringing silkworm eggs in their hollow staffs. Justinian was fully aware of the importance of his purchase and by a special decree ordered silkworms to be bred in eastern regions empire. However, sericulture soon fell into decline and only after the Arab conquests flourished again in Asia Minor, and later throughout North Africa, in Spain.

After IV crusade(1203-1204) silkworm eggs came from Constantinople to Venice, and since then silkworms have been quite successfully bred in the Po Valley. In the XIV century. sericulture began in the south of France. And in 1596, silkworms were first bred in Russia - first near Moscow, in the village of Izmailovo, and over time - in the more suitable southern provinces of the empire.

However, even after the Europeans learned to breed silkworms and unwind cocoons, most of the silk continued to be delivered from China. For a long time, this material was worth its weight in gold and was available only to the rich. Only in the twentieth century, artificial silk somewhat pressed natural silk on the market, and even then, I think, not for long - after all, the properties natural silk truly unique.
Silk fabrics are incredibly durable and last a very long time. Silk is lightweight and retains heat well. Finally, natural silk is very beautiful and lends itself to uniform dyeing.

Silkworm caterpillars are hatched from eggs (gren) at a temperature of 23-25 ​​degrees Celsius. In large sericulture farms, grena is placed in special incubators for this, where the required temperature and humidity are maintained. It takes 8-10 days for the eggs to develop, after which small, only about 3 mm long, larvae are born. They are dark brown in color and covered with tufts. long hair. Hatched caterpillars are transferred to a special aft shelf in a well-ventilated room with a temperature of 24-25 degrees Celsius. Each such bookcase consists of several shelves covered with a fine mesh.

On the shelves are fresh mulberry leaves. The caterpillars eat them with such gusto that Pasteur compared the loud crunch from the aft shelf to "the sound of rain falling on the trees during a thunderstorm."

The appetite of caterpillars is growing by leaps and bounds. Already on the second day after hatching, they eat twice as much food as on the first day, and so on. On the fifth day, the caterpillars begin to molt - they stop eating and freeze, clasping the leaf with their hind legs and raising the front of the body high. In this position, they sleep for about a day, and then the larva straightens up strongly, the old skin bursts, and the caterpillar, which has grown and covered with delicate new skin, crawls out of its tight clothes. Then she rests for a few hours and then starts eating again. Four days later, the caterpillar falls asleep again before the next molt ...

During its life, the silkworm caterpillar molts 4 times, and then builds a cocoon and turns into a chrysalis. At 20-25 degrees Celsius, the development of the larva is completed in about a month, with more high temperature- faster. After the fourth molt, the caterpillar already looks very impressive: its body length is about 8 cm, its thickness is about 1 cm, and its weight is 3-5 g. Its body is now almost naked and painted whitish, pearl or ivory. At the end of the body there is a blunt curved horn. The head of the caterpillar is large with two pairs of jaws, of which the upper one (mandibles) is especially well developed. But the main thing that makes the silkworm so attractive to humans is a small tubercle under the lower lip, from which a sticky substance oozes, which, when it comes into contact with air, immediately solidifies and turns into a silk thread.

Here, in this tubercle, the excretory ducts of two silk-secreting glands located in the body of the caterpillar flow. Each gland is formed by a long coiled tube, the middle part of which is expanded and turned into a reservoir in which the "silk liquid" accumulates. The reservoir of each gland passes into a long thin duct, which opens with an opening on the papilla of the lower lip. When the caterpillar needs to prepare a silk thread, it releases a trickle of liquid outward, and it freezes, turning into a paired thread. It is very thin, only 13-14 microns in diameter, but at the same time it can withstand a load of about 15 g.
Even the smallest caterpillar that has just emerged from the egg can already secrete a thin thread. Every time the baby is in danger of falling down, she releases a silk thread and hangs on it, like a spider hangs on its web. But after the fourth molt, the silk glands reach especially large sizes- up to 2/5 of the total body volume of the larva.

Now every day the caterpillar eats less and less and finally stops eating altogether. The mulberry gland at this time is already so full of liquid that a long thread stretches behind the larva, no matter where it crawls. Ready for pupation, the caterpillar crawls restlessly along the shelf in search of a suitable place to pupate. At this time, silkworm breeders place bundles of wood rods - cocoons on the aft whatnot along the side walls.

Having found a suitable support, the caterpillar quickly crawls onto it and immediately begins its work. Clinging tightly to one of the twigs with her abdominal legs, she throws her head to the right, then back, then to the left and applies her lower lip with a “silk” papilla to various places cocoon. Soon a rather dense network of silk thread is formed around it. But this is not the final building, but only its foundation. Having finished with the frame, the caterpillar crawls to its center - at this time, silk threads support it in the air and serve as the place where the real cocoon will be attached. And so his twist begins. Releasing the thread, the caterpillar quickly turns its head. For each turn, 4 cm of silk thread is required, and for the whole cocoon it takes from 800 m to 1 km, and sometimes more! As many as twenty-four thousand times the caterpillar must shake its head in order to spin a cocoon.

It takes about 4 days to make a cocoon. Having finished work, the exhausted caterpillar falls asleep in its silk cradle and turns into a chrysalis there. Some caterpillars, they are called carpet weavers, do not make cocoons, but, crawling back and forth, line the surface of the aft shelf like a carpet, while their chrysalis remains naked. Others, lovers of joint buildings, unite in twos or even threes and fours and weave a single, very large, up to 7 cm, cocoon. But these are all deviations from the norm. And usually the caterpillars weave a single cocoon, the weight of which, together with the pupa, is from 1 to 4 g.

The cocoons produced by spinning caterpillars are very diverse in shape, size, and color. Some of them are completely round, others are oval with a sharp end or constriction in the middle. The smallest cocoons do not exceed 1.5-2 cm in length, while the largest ones reach 5-6 cm. The color of the cocoons is completely white, lemon yellow, golden, dark yellow with a reddish tint, and even greenish, depending on the breed. silkworm. So, for example, a striped breed of silkworm spins pure white cocoons, and a stripless breed spins beautiful golden yellow cocoons.
Interestingly, the caterpillars, from which male butterflies are later obtained, are more diligent silkworms: they weave denser cocoons, which take more silk thread.

After about 20 days, a butterfly emerges from the chrysalis, which faces the problem of how to get out of its silk shelter. Indeed, unlike the caterpillar, it does not have sharp jaws ... However, the butterfly has another adaptation. Her goiter is filled with alkaline saliva, which softens the wall of the cocoon. Then the butterfly presses its head against the weakened wall, vigorously helps itself with its legs, and finally gets out. The silkworm butterfly does not shine with special beauty. The color of her plump hairy body is either white with a light cream pattern, or dark grayish brown. Females are larger than males.

The wingspan of the silkworm is about 4.5 cm, but these butterflies cannot fly. Most likely, they have lost this ability in the process of constant selection by man. After all, why are individuals that can fly away needed in silk farming?
Domestic butterflies generally do not tend to bother themselves with unnecessary movements. They only move slowly on their thin legs, and move their furry antennae. During their short (about 12 days) life, they do not even eat. After alkaline saliva is released from their mouth, softening the cocoon, it closes forever.

Male silkworms change their behavior only when they meet individuals of the opposite sex. That's when they come to life, circling around their girlfriend, constantly flapping their wings and actively sorting out their legs. During the mating season, the sericulture puts pairs of butterflies in special gauze bags. A few hours after prolonged mating, the female begins to lay eggs - from about 300 to 800. This process takes her 5-6 days. Silkworm eggs are small, about 1.5 mm long. In winter, the grena is kept at a relatively low temperature, and when spring comes and the leaves open on the mulberry trees, the eggs are gradually revived, first keeping them at a temperature of 12 degrees Celsius, and then placing them in a brood incubator.

But, of course, not every caterpillar that weaves a cocoon can turn into a butterfly. Most of the cocoons are used to obtain raw silk. The pupae are killed by steam, and the cocoons are soaked and unwound on special machines. About 9 kg of silk thread can be obtained from 100 kg of cocoons.
The silkworm spins the most beautiful yarn, but the caterpillars of some other butterflies are also capable of creating a silk thread, although coarser. So, from the cocoons of the East Asian satin (Attacus attacus) one obtains silk, and from the cocoons of the Chinese oak peacock-eye (genus Antheraea) - silk, which is used to make chesuchi.

A sticky substance is released from a small tubercle under the lower lip of the caterpillar, which, upon contact with air, immediately solidifies and turns into a silk thread. The thread is very thin, but can withstand weight up to 15 grams.

All modern domestic animals and cultivated plants are descended from wild species. Not without an insect on the farm - silkworm butterflies. Over four and a half millennia of breeding work, it was possible to breed breeds that give silk of different colors, and the length of a continuous thread from one cocoon can reach a kilometer! The butterfly has changed so much that it is now difficult to say who was its wild ancestor. In nature, the silkworm is not found - without human care, it dies.

Recall that many other caterpillars weave a cocoon of silky threads, but only in the silkworm they have the properties we need. Silk threads are used to produce fabrics that are very durable and beautiful; they are used in medicine - for sewing up wounds and cleaning teeth; in cosmetology - for the manufacture decorative cosmetics, such as shadows. Despite the advent of artificial materials, natural silk threads are still widely used.

Who first came up with the idea of ​​weaving silk fabric? According to legend, four thousand years ago, a silkworm cocoon fell into a cup of hot tea, which the Chinese empress drank in her garden. Trying to pull it out, the woman pulled on a protruding silk thread. The cocoon began to unwind, but the thread did not end. It was then that the quick-witted empress realized that yarn could be made from such fibers. The Chinese emperor approved the idea of ​​his wife and ordered his subjects to grow mulberry (white mulberry) and breed silkworm caterpillars on it. And to this day, silk in China is called the name of this ruler, and her grateful descendants elevated her to the rank of a deity.

It took a lot of work to get beautiful silk from butterfly cocoons. To begin with, the cocoons need to be collected, discarded and, most importantly, unwound, for which they were dipped into boiling water. Next, the thread was strengthened with sericin - silk glue, which was then removed with boiling water or hot soapy water.

Before dyeing, the thread was boiled and bleached. They painted it with vegetable pigments (gardenia fruits, moraine roots, oak acorns), or mineral pigments (cinnabar, ocher, malachite, white lead). And only then they wove yarn - by hand or on a loom.

As early as one and a half thousand years BC, clothes made of silk fabrics were common in China. In others Asian countries and among the ancient Romans, silk appeared only in the 3rd century BC - and then it was fabulously expensive. But the manufacturing technology of this amazing fabric remained a secret for the whole world for many centuries, because an attempt to take the silkworm out of the Chinese Empire was punishable by death. The nature of silk seemed mysterious and magical to Europeans. Some believed that silk was produced by giant beetles, others believed that in China the earth was soft, like wool, and therefore, after watering, it could be used to produce silk fabrics.

The secret of silk was discovered in the 4th century AD, when a Chinese princess presented a gift to her fiancé, the king of Lesser Bukhara. These were silkworm eggs, which the bride secretly took out of her homeland, hiding in her hair. Around the same time, the secret of silk became known to the Japanese emperor, but here sericulture for some time was the monopoly of the imperial palace alone. Then silk production was mastered in India. And from there, with two monks who placed silkworm eggs in the hollow handles of their staffs, they ended up in Byzantium. In the 12th-14th centuries, sericulture flourished in Asia Minor, Spain, Italy and France, and in the 16th century it appeared in the southern provinces of Russia.

Silkworm pupa

However, even after the Europeans learned to breed silkworms, most of the silk continued to be delivered from China. Along the Great Silk Road - a network of roads running from east to west - it was taken to all countries of the world. Silk outfits remained a luxury item, silk also served as an exchange currency.

How does a small white butterfly live - "silk queen"? Its wingspan is 40-60 millimeters, but as a result of many years of cultivation, butterflies have lost the ability to fly. The mouth apparatus is not developed because the adult does not feed. Only the larvae differ in an enviable appetite. They are fed with mulberry leaves. When feeding on other plants that the caterpillars "agree" to eat, the quality of the fiber deteriorates. On the territory of our country, representatives of the family of true silkworms, to which the silkworm belongs, are found in nature only in the Far East.

Silkworm caterpillars hatch from eggs, the laying of which is covered with a dense shell and is called grena. In sericulture farms, grena is placed in special incubators, where the necessary temperature and humidity are maintained. After a few days, small, three-millimeter dark brown larvae appear, covered with tufts of long hair.

Hatched caterpillars are transferred to a special aft shelf with fresh leaves mulberries. After several molts, the babies grow up to eight centimeters, and their bodies become white and almost naked.

The caterpillar, ready for pupation, ceases to feed, and then wood rods are placed next to it, to which it immediately passes. Holding on to one of the rods with its abdominal legs, the caterpillar throws its head to the right, then back, then to the left and applies its lower lip with a "silk" tubercle to various places on the rod.

Caterpillars are fed with mulberry leaves.

Soon a rather dense network of silk thread is formed around it. But this is only the basis of the future cocoon. Then the "craftswoman" crawls to the center of the frame and begins to curl the thread: releasing it, the caterpillar quickly turns its head. The tireless weaver works on the cocoon for about four days! And then it freezes in its silk cradle and turns into a chrysalis there. After about 20 days, a butterfly emerges from the chrysalis. She softens the cocoon with her alkaline saliva and, helping herself with her legs, hardly gets out to start looking for a partner for procreation. After mating, the female lays 300-600 eggs.

However, not every caterpillar is given the opportunity to turn into a butterfly. Most cocoons are sent to the factory to obtain raw silk. One centner of such cocoons yields approximately nine kilograms of silk thread.

It is interesting that the caterpillars, from which males are later obtained, are more diligent workers, their cocoons are denser, which means that the thread in them is longer. Scientists have learned to regulate the sex of butterflies, increasing the yield of silk during its industrial production.

Such is the story of the small white butterfly that made ancient China famous and made the whole world worship its magnificent product.

Olga Timokhova, Candidate of Biological Sciences

The history of breeding such an insect as the silkworm is extremely interesting. The technology was developed a long time ago, in ancient China. The first mention of this production in Chinese chronicles dates back to 2600 BC, and silkworm cocoons found by archaeologists date back to 2000 BC. e. The Chinese elevated silk making to the status of a state secret, and for many centuries this was the country's clear priority.

Much later, in the 13th century, Italy, Spain, countries began to breed and produce such worms. North Africa, and in the 16th century - and Russia. What kind of insect is the silkworm?

Silkworm butterfly and its offspring

The domesticated silkworm butterfly is not found today in wild nature and is bred in special factories to obtain a natural thread. An adult is enough large insect light in color, reaching 6 cm in length with a wingspan of up to 5-6 cm. Breeding various breeds of this interesting butterfly engaged in breeders in many countries. After all, optimal adaptation to the characteristics of various localities is the basis for profitable production and maximum income. Many breeds of silkworm have been bred. Some give one generation a year, others two, and there are species that give several broods a year.

Despite its size, the silkworm butterfly has long lost this ability. She lives only 12 days and during this time she does not even eat, having an undeveloped oral cavity. With the onset mating season silkworm breeders deposit pairs in separate bags. After mating, the female for 3-4 days is engaged in laying eggs in the amount of 300-800 pieces in a grain, which has an oval shape with significantly varying sizes, which are directly dependent on the breed of the insect. The period of removal of the worm also depends on the species - it can be in the same year, or maybe in the next.

Caterpillar - the next stage of development

The silkworm caterpillar hatches from eggs at a temperature of 23-25 ​​°C. In the factory, this happens in incubators at a certain humidity and temperature. The eggs develop within 8-10 days, then a brown small up to 3 mm long silkworm larva, pubescent with hairs, appears from the grena. Small caterpillars are placed in special trays and transferred to a well-ventilated warm room. These containers are a structure like a bookcase, consisting of several shelves, covered with a net and having a specific purpose - here the caterpillars constantly eat. They feed exclusively on fresh mulberry leaves, and the proverb “appetite comes with eating” is absolutely accurate for determining the voracity of caterpillars. The need for food grows in them and already on the second day they eat twice as much food as on the first.

Moult

By the fifth day of life, the larva stops, freezes and begins to wait for its first molt. She sleeps for about a day, clasping her legs around a leaf, then, with a sharp straightening, the skin bursts, releasing the caterpillar and giving it the opportunity to rest and again take up satisfying hunger. For the next four days, she absorbs the leaves with an enviable appetite, until the next molt comes.

caterpillar transformations

For the entire period of development (about a month), the caterpillar molts four times. The last molt turns it into a fairly large individual of a magnificent light pearl shade: the body length reaches 8 cm, the width is up to 1 cm, and the weight is 3-5 g. It stands out well on the body with two pairs developed jaws, especially the upper ones, called "mandibles". But the most important quality that is important for the production of silk is the presence in an adult caterpillar of a tubercle under the lip, from which a special substance oozes, which hardens on contact with air and turns into a silk thread.

The formation of a silk thread

This tubercle ends with two silk glands, which are long tubes with a middle part turned into a kind of reservoir in the body of the caterpillar, accumulating a sticky substance, which subsequently forms a silk thread. If necessary, the caterpillar releases a trickle of liquid through the hole under the lower lip, which solidifies and turns into a thin, but strong enough thread. The last one in the life of an insect plays big role and is used, as a rule, as a safety rope, since at the slightest danger it hangs on it like a spider, not being afraid to fall. In an adult caterpillar, silk glands occupy 2/5 of the entire body weight.

Stages of building a cocoon

Having reached adulthood after the 4th molt, the caterpillar begins to lose its appetite and gradually stops eating. The silk secreting glands by this time are filled with liquid so that a long thread constantly stretches behind the larva. This means that the caterpillar is ready to pupate. She begins to look for a suitable place and finds it on cocoon rods, promptly placed by silkworm breeders along the side walls of the stern "shelves".

Having settled on a twig, the caterpillar begins to work intensively: it alternately turns its head, applying a tubercle with a hole for the silk gland to different places on the cocoon, thereby forming a very strong network of silk thread. It turns out a kind of frame for future construction. Then the caterpillar crawls to the center of its frame, holding itself in the air by means of threads, and begins to spin the actual cocoon.

Cocoon and pupation

When building a cocoon, the caterpillar turns its head very quickly, releasing up to 3 cm of thread on each turn. Its length to create the entire cocoon is from 0.8 to 1.5 km, and the time spent on it takes four or more days. Having finished work, the caterpillar falls asleep in a cocoon, turning into a chrysalis.

The weight of the cocoon together with the chrysalis does not exceed 3-4 g. Silkworm cocoons are very diverse in size (from 1 to 6 cm), shape (round, oval, with bridges) and color (from snow-white to golden and purple). Experts have noticed that male silkworms are more diligent in terms of cocoon weaving. Their pupal dwellings are distinguished by the density of the winding of the thread and its length.

And again a butterfly

After three weeks, a butterfly emerges from the chrysalis, which needs to get out of the cocoon. This is difficult, since it is completely devoid of jaws that adorn the caterpillar. But wise nature solved this problem: the butterfly is equipped with a special gland that produces alkaline saliva, the use of which softens the wall of the cocoon and helps to release the newly formed butterfly. So the silkworm completes the circle of its own transformations.

However, industrial breeding of the silkworm interrupts the reproduction of butterflies. The bulk of the cocoons is used to produce raw silk. After all, this is a finished product, it remains only to unwind the cocoons on special machines, after killing the pupae and treating the cocoons with steam and water.

So, the silkworm, the cultivation of which on an industrial scale will probably never lose its relevance, is a magnificent example of a domesticated insect that brings a very considerable income.