Silkworm. Silkworm cocoons. Features, characteristics, reproduction and why does a person need a silkworm? Looks like a silkworm

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The silkworm (lat. Bombyx mori) is a nondescript little butterfly with off-white wings that can't fly at all. But it is thanks to her efforts that women of fashion all over the world for more than 5,000 years have been able to enjoy outfits made of beautiful soft fabric, the brilliance and colorful transfusion of which fascinate at first sight.

flickr/c o l o r e s s

Silk has always been a valuable commodity. The ancient Chinese - the first manufacturers of silk fabric - kept their secret securely. For its disclosure relied on immediate and terrible the death penalty. They domesticated silkworms as early as the 3rd millennium BC, and to this day these small insects work to satisfy the vagaries of modern fashion.

flickr/Gustavor..

There are monovoltine, bivoltine and polyvoltine breeds in the world silkworm. The former give only one generation per year, the latter two, and the third several generations per year. An adult butterfly has a wingspan of 40-60 mm, it has an underdeveloped oral apparatus, so she does not eat throughout her short life. The wings of the silkworm are off-white in color, brownish bandages are clearly visible on them.

flickr/janofonsagrada

Immediately after mating, the female lays eggs, the number of which varies from 500 to 700 pieces. The laying of a silkworm (like all other representatives of the peacock-eye family) is called grena. It has an elliptical shape, flattened on the sides, with one side slightly larger than the other. On a thin pole there is a recess with a tubercle and a hole in the center, which is necessary for the passage of the seed thread. The size of the grena depends on the breed - in general, Chinese and Japanese silkworms have less grena than European and Persian ones.

flickr/basajauntxo

Silkworms (caterpillars) emerge from the egg, to which all the views of silk producers are riveted. They grow in size very quickly, shedding four times in their lifetime. The entire cycle of growth and development lasts from 26 to 32 days, depending on the conditions of detention: temperature, humidity, food quality, etc.

flickr/Rerlins

Silkworms feed on the leaves of the mulberry tree (mulberry), so silk production is possible only in places where it grows. When the time of pupation comes, the caterpillar wraps itself in a cocoon, consisting of a continuous silk thread with a length of three hundred to one and a half thousand meters. Inside the cocoon, the caterpillar transforms into a chrysalis. In this case, the color of the cocoon can be very different: yellowish, greenish, pinkish or some other. True, only silkworms with white cocoons are bred for industrial needs.

flickr/JoseDelgar

Ideally, the butterfly should leave the cocoon on the 15th-18th day, however, unfortunately, it is not destined to live up to this time: the cocoon is placed in a special oven and kept for about two to two and a half hours at a temperature of 100 degrees Celsius. Of course, the pupa dies, and the process of unwinding the cocoon is greatly simplified. In China and Korea, fried pupae are eaten, in all other countries they are considered just “production waste”.

flickr/Roger Wasley

Sericulture has long been an important industry in China, Korea, Russia, France, Japan, Brazil, India and Italy. Moreover, about 60% of all silk production falls on India and China.

The history of silkworm breeding

The history of breeding this butterfly, belonging to the family of real silkworms (Bombycidae), is associated with ancient China, a country long years which 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 he ordered silkworms to be bred in the eastern regions of the 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 they have been quite successfully bred in the Po Valley silkworms. 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 20th 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.

Used sources.

Silk caterpillar in 30 days increases in weight by 10 thousand times

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 silkworm. 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.

Extremely interesting breeding history such an insect as the silkworm.

The technology was developed a very 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.

The ancient Chinese philosopher Confucius retells the legend of how man first learned about the silk thread. Empress Xi-Ling-shi found a cocoon under a mulberry bush and mistook it for some wondrous fruit. But he accidentally fell out of her hands into a cup of tea. Trying to get it, the empress pulled out a silk thread. In gratitude for this accidental discovery, the Chinese elevated Xi-Ling-shi to the rank of a deity of the Celestial Empire. At first, only empresses and women from among their entourage were engaged in the production of silk.

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 are revealed someday. This happened with the production of silk. First, some selfless Chinese princess in in. BC, 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 on a journey and returned the same year, bringing silkworm eggs in their hollow staffs. Justinian was fully aware of the importance of his purchase and ordered silkworms to be bred in the eastern regions of the empire by special decree. However, sericulture soon fell into decline and only after the Arab conquests flourished again in Asia Minor, and later in North Africa, in Spain. Much later, in the 13th century, Italy, countries began to breed such worms and produce silk fabric. North Africa, and in the 16th century - and Russia.

The "Great Silk Road" - a caravan road that in ancient times connected the West with the East and stretched through the mountains of Central and Central Asia - served the development of geography as a science and trade between ancient countries.

In the 20th century, silk had a serious rival - artificial and then synthetic chemical fibers. Many of them are stronger than silk, less wrinkled, more resistant to abrasion, but a person feels better in clothes made from natural silk.

Butterfly with big wings

What kind of insect is the silkworm?

The silkworm is not found today in wild nature and is bred in special factories to obtain a natural thread. An adult is a rather large insect - a butterfly light color, reaching 6 cm in length with a wingspan of up to 5-6 cm. By 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. The silkworm cannot live without human care, it is not able to survive 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.

Many silkworm breeds have been bred: monovoltine - they give one generation a year, polyvoltine - two, and there are species that give several broods a year. Despite its size, the silkworm butterfly does not fly, as it has long lost this ability. She lives only 12 days and during this time she does not even eat, having an undeveloped oral cavity.

Butterfly and ... Butterfly again

With the onset mating season silkworm breeders plant pairs of butterflies in separate bags. After mating, the female spends 3-4 days laying eggs in the amount of 300-800 pieces per 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 in the development of the silkworm cocoon. 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 fresh leaves mulberry, and the proverb “appetite comes with eating” is absolutely accurate for determining the voracity of caterpillars. Their need for food grows exponentially, already on the second day they eat twice as much food as on the first. A silkworm in 30 days increases in weight by 10,000 times.

Molt. By the fifth day of life, the larva stops, freezes and begins to wait for its first molt. When the color of the head of the caterpillar darkens, it means that the molt has begun. 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 rather 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 with dense skin. Exudes on the body big head with two pairs of well-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.

Formation of 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 latter plays a big role in the life of an insect 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. Silkworm caterpillars use a continuous silk thread to curl their cocoons, the length of which is 300-900 meters, there were also large cocoons that were “wound” from 1500 meters of threads. 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 silkworm interrupts the reproduction of butterflies. The bulk of the cocoons is used to produce raw silk. After all, this is already finished product, it remains only to unwind the cocoons on special machines, after killing the pupae and treating the cocoons with steam and high temperature water (100 degrees), and the cocoon unwinds very easily after that. So, the silkworm, whose breeding in industrial scale, probably never loses its relevance, - a magnificent example of a domesticated insect that brings a very considerable income.

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.

Useful properties of silk thread

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 of this substance are lost in the process of making a silk cloth, but even the little that remains in the silk fibers can save the fabric from the appearance of a dust mite.

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. This is ideal protein product , it is widely used in Asian cuisine. In China, the larvae are steamed and grilled, seasoned, usually with a huge amount of spices you don’t even understand what “is on the 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”.

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.

At the end of the nineteenth century, a man came up with the idea to bring the new kind he planned to cross the silkworm and the gypsy moth. To get an insect that will be less "fastidious in food", but at the same time it must produce silk thread. For this purpose, a batch of gypsy moth cocoons was brought from Europe to America. The experiment is over complete failure. The scientist failed to cross these types of silkworms, but the gypsy moth is “comfortably” located in America and is now harming the forestry of the United States of America.

Only the facts

• Silk thread is very strong, able to withstand great pressure. Ropes made of silk are more efficient than ropes made of steel of the same thickness.
• It takes about 3,000 silkworm cocoons to produce 1m of silk fabric.
• Almost 80% of the world's silk production belongs to China.

To create a silk thread sufficient to produce fabric for 1 dress, silkworms need to eat about 70 kg of leaves.

1 silkworm caterpillar, from its transformation into a chrysalis, eats mulberry leaves, which are 40 thousand times larger in mass than its weight.

1 silkworm caterpillar in 4 weeks from the moment of its birth increases in size by 25 times, its mass increases by 12 thousand times.

The speed at which the silkworm produces its thread can be 15 meters per minute.

The silkworm caterpillar weaves its cocoon in 3-4 days.





Here is a useful silkworm.

These butterflies are used by humans to obtain silk; in general, the silkworm is a very old inhabitant of our planet. Some argue that people began to use it as early as five thousand years BC.

Today, the worms of this butterfly are bred for silk, Interesting Facts that in China and Korea, silkworm cockles are used for food, they are fried and such a dish is considered exotic, and these larvae are also used in folk medicine.

In our world, the most important countries that produce silk (60 percent of the total market) are India and China, where silkworms live the most.

Today, people know much more about the production and types of silk than about the insect that gave us this magnificent silk thread. We will talk about this in this article. We will find out what the silkworm looks like, what it eats, how it is bred, as well as its breeding characteristics.

Appearance

Silkworms got their name from their diet. They recognize only one tree - this is mulberry, in scientific language this tree is called mulberry. Silkworm caterpillars eat day and night without stopping. Therefore, some farm owners get inconvenienced if the tree is occupied by caterpillars of this breed. In the silk industry, the mulberry tree is specially grown to provide food for silkworms.

This insect goes through a standard development process, which can be seen in the video. Like all insects, the wild silkworm goes through four life cycles, namely:

• the formation of an egg (larva);
• the appearance of a caterpillar;
• pupa formation (silkworm cocoons);
• butterfly.

The butterfly is quite large. The wingspan is about 60 millimeters. Back to main features appearance include the following indicators:

• the color is white with dirty spots;
• brown clear dressings on the wings;
• the front part of the wing is notched;
• males have comb whiskers, while females have this effect weakly expressed;

Outwardly, the wild silkworm is very beautiful. In the photo and video you can see how this breed of butterflies looks in life.

To date, this species practically does not fly, due to the content in unnatural conditions. There are also interesting facts that state that these insects do not eat when they become butterflies. This breed has obvious distinctive features from all other species. The fact is that for many centuries, a man kept a silkworm at home and therefore, today these butterflies cannot survive without his care and guardianship. For example, caterpillars will not look for food, even if they are very hungry, they will wait for a person to feed them. To date, scientists cannot give an exact answer about the origin of this species.

In modern sericulture, there are many varieties of silkworms. Most often, hybrid individuals are used. In general, this breed can be divided into two types:

• the first is monovoltine, such a species can give offspring no more than once a year;
• the second is polyvoltine, which produces larvae several times a year.

Hybrids are different outward signs, which include:

• wing color;
• body shape;
• the dimensions that characterize the pupa;
• shapes and sizes of butterflies;
• the size and color of the caterpillars (there is a breed of silkworm with striped caterpillars or one-color ones).

How all possible types of silkworms look can be seen in the photo or video.

The indicators of silkworm productivity include the following characteristics:

• the amount of output of dry cocoons and their total yield;
• how much cocoon shells can unwind;
• silk output;
• technical properties and quality of the resulting silk.

What are the characteristics of silkworm eggs?

In the scientific field, silkworm eggs are called grena. Features are as follows:

• oval shape;
• slightly flattened sides;
• elastic and translucent shell.

The size of the egg is incredibly small, in one gram there can be up to two thousand eggs. As soon as the butterflies have laid grena, it has a light yellow or milky color, and over time the color of the eggs gradually changes, at first turning a little pink and finally becoming dark purple. And when the color of the eggs does not change, this indicates that their vitality has been completely lost.

The ripening period of grena is long. Butterfly larvae are laid in July and August. Then they hibernate until spring. During this period, all metabolic processes in the egg slow down significantly. This is necessary so that the grena can transfer low temperatures, and the appearance of caterpillars was regulated. For example, if in winter the eggs were at a temperature not lower than +15 degrees, then future caterpillars develop very poorly. This is due to the fact that they hatch very early, even before the mulberry leaves appear (this main source food for silkworms). Therefore, during this period, the eggs are placed in the refrigerator, where a constant temperature is observed. temperature regime from 0 to -2 degrees.

Life cycle of caterpillars

The appearance of caterpillars refers to the larval stages of development of silkworms. They used to be called silkworms, but based on scientific terms, this name is incorrect. To external characteristics caterpillars include the following indicators:

• the body has a slightly elongated shape;
• there is a head, abdomen and chest;
• there are horny appendages on the head;
• on the inside of the body there are three pairs of pectoral, and five abdominal legs;
• caterpillars have chitinous covers that perform protective function and at the same time are their muscles.

The external data of the caterpillars can be found in the photo, as well as see them life cycle on video.

Once a caterpillar hatches from an egg, it is very small, weighing only half a milligram. But with such a small size and weight, the body of the caterpillars has all the necessary biological processes for a full life, so they grow rapidly. In the body of a caterpillar there are very powerful jaws, esophagus, developed pharynx, intestines, circulatory and excretory system. Thanks to such a developed organism, all the food consumed is very well absorbed. Imagine that these babies have more than four thousand muscles, which is eight times more than humans. Acrobatic numbers that caterpillars can perform are associated with this.

The life cycle of a caterpillar lasts about forty days, during which time it increases in size by more than thirty times. Due to this intensity of growth, the shell with which the caterpillars are born becomes small, so they need to shed their old skin. This process is called molting. During this period, individuals stop feeding and find a place to molt. Tightly attaching their legs to the leaves, or holding on to a tree, they freeze. In the people, this period is called sleep. This spectacle can be seen in detail in the photo. Then the caterpillar, as it were, hatches again from the old skin. First, the head appears, which has increased several times in size, and then the rest of the body. During sleep, the caterpillars cannot be touched, otherwise they will not be able to throw off the old cover, as a result of which they die.

For all your life span caterpillars go through the process of molting four times. And each time they have a different color. In the photo and video you can see the colors of the caterpillars.

The main part of the caterpillar's body for humans is the silk gland. This organ is best developed, thanks to artificial content for many centuries. In this organ, the silk we need is formed.

Final stage of development: silkworm chrysalis

Silkworm cocoons are formed for a short time (you can see them in the photo) This is an intermediate stage of development. The caterpillar forms a chrysalis around itself and stays there until it turns into a butterfly. Such silkworm cocoons are the most valuable for humans. Many amazing processes take place inside the cocoon, the caterpillar goes through the stage of the last molt and turns into a chrysalis, and then it becomes a butterfly.

The appearance of a butterfly and its departure can be easily determined. The day before the emergence of cocoons begin to move. If you lean against the cocoon at this time, you can hear a small noise, like tapping. This butterfly sheds its pupa skin. Interestingly, butterflies appear strictly at the allotted time. This is the period from five to six in the morning.

In order to get out of the cocoon, the mucous membranes of the butterfly secrete a specialized glue that splits the cocoon and makes it possible to fly out (newborn butterflies can be seen in the photo).

Butterflies live very little, no more than 18-20 days, but there are also centenarians who can reach the age of 25-30 days. The jaws and mouth of butterflies are undeveloped, so they cannot eat. During this short life span, their main purpose is to mate and lay eggs. One female can lay more than one thousand eggs per clutch. The laying process does not stop, even if the female does not have a head, because there are several nervous systems. In order to provide future offspring with good survival, the females attach the gren very strongly to the surface of the leaf or to the tree. That's all! This is where the life cycle of silkworms ends.

Then the process begins again, and goes through all the above stages again, supplying humanity with a silk thread.

Class - Insects

Detachment - Lepidoptera

Family - silkworms

Genus/Species - bombyx mori

Basic data:

DIMENSIONS

Length: caterpillar - 8.5 cm.

Wingspan: 5 cm

Wings: Two pairs.

Mouth apparatus: the caterpillar has one pair of jaws, while the adult butterfly has atrophied mouthparts.

BREEDING

Number of eggs: 300-500.

Development: from egg to pupa - time depends on temperature; from pupa to hatching butterfly 2-3 weeks.

LIFE STYLE

Habits: mulberry silkworm (see photo) is a domesticated insect species.

What does it eat: mulberry leaves.

Lifespan: an adult silkworm lives 3-5 days, a caterpillar - 4-6 weeks.

RELATED SPECIES

There are about 300 species of silkworms in the world, such as oak Chinese silkworm and atlas.

The ancient Chinese domesticated the silkworm 4,500 years ago. They obtained silk from cocoons woven by silkworm caterpillars to turn into an adult butterfly. A beautifully woven cocoon of a silkworm is formed by a single silk thread, the length of which can reach one kilometer.

SILKMOTH AND MAN

A natural fiber called silk is also produced by many other types of insects, but only the silkworm produces enough of it. in large numbers and also different high quality, therefore it is advantageous to breed the silkworm in captivity. The ancient Chinese invented a way to unwind the fiber and turn it into a strong thread. The first silk products appeared from the cocoons of wild silkworms. However, soon the Chinese began to breed them in artificial conditions and sought to choose as large and heavy cocoons as possible for further breeding. As a result of such attempts, modern silkworms were bred, which are much larger than their wild ancestors. True, they do not know how to fly and are completely dependent on humans.

Silkworm cocoons are softened with hot steam, put in hot water, and then unwound at special factories, getting yarn. To make fabrics, the threads are always twisted several threads together because they are very thin.

LIFE CYCLE

The silkworm is currently not found in the wild. The ancient Chinese domesticated the silkworm 4,500 years ago. Since all this time a careful selection of individuals was carried out for their further breeding in captivity, the modern silkworm is much larger than its distant ancestor. Also, he is unable to fly. The caterpillar reaches its maximum size six weeks after birth. Before the formation of a cocoon, she stops feeding, becomes restless, crawls back and forth in search of a convenient place to securely attach herself. Attached to the stem, the caterpillar begins to spin a silk cocoon. Silk fiber is a secretion of paired arachnoid glands, which are located in several longitudinal folds on the body of the caterpillar and reach its lower lip. When turning into a chrysalis, the caterpillar releases one whole thread up to 1 kilometer long, which it wraps around itself. Silkworm cocoons can be different color- yellowish, white, bluish, pink or greenish. After the transformation of the caterpillar into a chrysalis, the next stage begins - the transformation into an adult butterfly.

WHAT DOES IT FEED

Caterpillars should eat almost continuously. They feed on mulberry leaves, eating them at an incredible rate.

The caterpillar, born from an egg, has a length of 0.3 cm and weighs 0.0004 g, and after a while its length is already up to 8.5 cm, and its weight is 3.5 g. Sometimes the caterpillars also eat the leaves of other plants . However, observations have shown that caterpillars that are fed a mixed diet grow much more slowly, and the quality of the silk fiber they produce changes - the thread becomes thicker than that of caterpillars that were fed only mulberry leaves. Caterpillars grow up to 6 weeks, then they stop eating and spin a cocoon, inside which they turn into an imago (adult).

GENERAL PROVISIONS

Now cheap synthetic fabrics have greatly supplanted natural silk, and yet products made from it, as before, remain popular.

As early as 4,000 years ago, silkworms were bred in China to produce silk. For a long time already, this moth and its larvae cannot exist without human help. Adult insects have completely lost the ability to fly, and caterpillars would rather die of starvation than crawl in search of suitable food. For more than 2,000 years, China has maintained a monopoly on sericulture. For any attempt to take out grena (silkworm egg laying), the death penalty threatened. There was an ancient caravan route, which was called - "The Great silk road". The fact is that silk fabrics were very much appreciated in the countries of Europe and the Middle East. And not only for the beauty of silk clothes. The most important thing is that in such clothes a person was less bothered by lice and fleas! That is why for many centuries the silk trade has been the main source of income for the people of China. In 552, the pilgrim monks managed to deliver the silkworm to Constantinople. Then Emperor Justinian issued a special order, which ordered to engage in sericulture in the Byzantine Empire. China's monopoly on silk has come to an end. AT Western Europe they began to breed silkworms in 1203-1204, when the Venetians, after the IV Crusade, brought silkworm gren to their homeland.

INTERESTING FACTS. DO YOU KNOW WHAT...

• The annual production of raw silk is about 45 thousand tons. The main producers are Japan and China, South Korea, Uzbekistan and India.
• According to legend, the silkworm came to Europe thanks to two monks who hid it in a reed.
• Legend has it that China lost its monopoly on silk production in 400 AD, when a Chinese princess married an Indian raja while leaving her country and secretly took silkworm eggs with her.
• Silk from silkworm threads is called "noble" silk.
• Silk yarn is made from the silk of the Chinese oak silkworm (Chinese oak saturnia).

LIFE CYCLE OF THE SILKMOTH

Eggs: the female lays up to 500 eggs per leaf and dies soon after.

Larvae, hatched from eggs, black, covered with hairs. Hatching time depends on temperature.

Caterpillar: during development, the larva molts several times until it is white and smooth, without eyelashes.

Cocoon: the caterpillar intensively feeds on leaves for 6 weeks, and then begins to look for a suitable twig. On it she spins a cocoon, from silk, with which she surrounds herself.

Adult silkworm: the butterfly mates shortly after emerging from the cocoon. The female secretes a special substance with a strong odor, which the male catches. By smell, with the help of special hairs on enlarged antennae, the male determines the location of the female.

WHERE Dwells

The silkworm is native to Asia. Nowadays, silkworms are grown in Japan and China. There are many farms in India, Turkey, Pakistan, as well as in France and Italy.

PROTECTION AND PRESERVATION

The ancient Chinese domesticated the silkworm 4,500 years ago. Now the silkworm is bred on special farms.

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