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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 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 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 enough large insect- a light-colored butterfly, 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 maximizing 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 on fresh mulberry leaves, 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. A large head stands out on the body 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 of the silkworm interrupts the reproduction of butterflies. The bulk of the cocoons is used to produce raw silk. After all, this is already 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 high temperature(100 degrees), and the cocoon unwinds very easily after that. 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.

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 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 with a huge amount of spices you don’t even understand what “is on the plate”.

In Korea they eat half-baked silkworms, for this 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 ended in 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. Silk ropes 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.

Views: 3478

13.06.2017

With the history of the silkworm, thanks to which such a wonderful fabric as natural silk appeared ( lat. Mulberry) is associated with a huge number of ancient fictions and legends.

This amazing quality material is produced by caterpillars, which, eating the leaves of the mulberry tree (for us, the name mulberry is more familiar), process them, creating a surprisingly thin and strong silk thread from which they weave their cocoons.

silkworm ( lat. bombyx mori ) is a butterfly from the insect family " real silkworms", a " bombyx mori» translated from Latin literally means "death of a silkworm" or "dead silk". Such a tragic name is explained by the fact that a living butterfly is specifically not allowed to leave the cocoon, so the insect, suffocating, dies inside it (more on this sad fact a little later in the text).

Cocoons can be of various colors and shades, which depends primarily on the type of silkworm, but White color considered to be of the highest quality because it contains the most high percent silk protein.

Currently, silk production is most developed in China, Japan and India.

adult insect

It is assumed that the silkworm moth originated from its wild relative, which previously lived in the mulberry thickets of ancient China. According to some historical data, the culture of creating silk originated about five thousand years ago, and during this time the insect was completely domesticated and even lost the ability to fly (only male insects fly during the mating period).

The silkworm butterfly is a rather large insect with a wingspan of up to six centimeters. It is noteworthy that immediately before pupation, it can increase in height up to nine (!) Centimeters.

Egg

Having hatched from a cocoon, an adult female mates with a male, after which she lays eggs for four to six days, covering them with a dense shell called grenay. During this period, the moth does not eat anything, since its oral apparatus is underdeveloped.

Silkworm embryos are small and have a light yellow or milky color. Having laid from three hundred to six hundred eggs (sometimes the number of eggs in an oviposition can reach eight hundred), the silkworm butterfly dies.

Larva

After about a week, a small dark brown larva emerges from the embryo (the silkworm caterpillar is often called " silkworm”) about two to three millimeters long.

From birth, the larva has an excellent appetite, so it feeds around the clock, eating juicy mulberry leaves with pleasure.

Silkworm caterpillars are very sensitive to temperature and humidity, they are not tolerant of pungent odors and cannot stand loud sounds, but if external conditions habitats are quite favorable, the larvae are rapidly gaining weight, day by day, increasing the rate of consumption of plant foods. In the rooms where silkworms are grown, the monotonous work of many jaws is a continuous hum, as if a fine rain is drumming on a metal roof.

It is hard to imagine that these babies have more than four thousand muscles in their crumbled body, which is eight times (!) More than a person.

During the growing season, the silkworm larva goes through four stages or phases of maturation, and the first molt occurs already on the fifth day from the date of birth, while the caterpillar stops feeding, and firmly clinging to the leaf, hibernates for a day. Waking up, the caterpillar sharply straightens its body, which is why the old skin bursts and the grown insect, freed from its former clothes, with new force pounces on food.

After four molts, the body of the caterpillar increases in size by more than thirty (!) Times and their body acquires a yellowish tint.

chrysalis

In total, the silkworm caterpillar grows and develops for about a month, and immediately before pupation, the larva loses all interest in food.

Under the lower lip of the insect there are special glands capable of producing a silky gelatinous substance, which, when hardened, turns into a thin silk thread.

Silkworm thread is ninety percent protein. In addition, it contains salts, fats, wax and a sticky substance. sericin, which prevents the threads from disintegrating tightly fastening them to each other.

When the time comes, the caterpillar fixes its body on a strong base and begins to form a frame around itself in the form of a fine mesh, and then weaves the cocoon itself, winding the thread around itself in a “figure eight”.

After three or four days, the cocoon is completely ready, and the total length of the thread in the finished cocoon can reach from three hundred meters to one and a half (!) kilometers.

It is noteworthy that male silkworms make cocoons more scrupulously, so they are somewhat denser to the touch, and the length of the silk thread in the male cocoon is longer.

After about eight to nine days, the cocoons can be collected and spun to produce a thread of unique quality. If this process is late, then an adult insect will come out of it ( imago) in the form of a butterfly, which will damage the shell of the cocoon and the thread will eventually be torn.

As mentioned earlier, the butterfly has an underdeveloped mouth apparatus, therefore it is not able to gnaw through the shell of the cocoon and, in order to fly out, it secretes a special substance with saliva that dissolves upper part cocoon, damaging the threads. To avoid this, butterflies are artificially killed right in their cocoons with the help of hot air, processing the pupae for two hours. This process kills the butterfly, so that the name of this insect species (" Death of the silkworm") is fully justified.

After the thread is unwound, the dead chrysalis is eaten (typically in China and Korea) because it is rich in protein and nutrients.

The process of creating silk thread

Currently, the silkworm is grown mainly artificially.

Cocoons are collected, sorted by color, size and prepared for subsequent unwinding, for which they are dipped in boiling water. This process is still done by hand, because the thread of the cocoon is very thin and requires special care to unwind it.

To create a raw thread, when unwinding, from three to ten silk threads are connected together, and all the same natural sericin helps to carefully fasten all the ends.

Raw silk is wound into yarn and sent to a weaving factory for further processing and production. wonderful fabric highly valued all over the world.

Legend has it that the first person who came up with the idea of ​​weaving silk thread was the legendary Chinese Empress Lei Zu (also known as Xi Lingshi), walking in a mulberry garden with a cup of hot tea, into which a silkworm cocoon suddenly fell. Trying to get it, the empress pulled a thin thread, which caused the cocoon to unwind.

Lei Zu convinced her husband (the legendary ruler of China, Huangdi or " yellow emperor"") to provide her with a grove of mulberry trees where she could breed caterpillars that produce cocoons. She is also credited with inventing a special spool that combines thin threads into one strong thread suitable for weaving, and inventing the silk loom.

In modern China, Lei Zu is an object of worship and bears the honorary title " Mother of the Silkworm».

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 caterpillar, moves on 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” until 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 fundamentally different from the "home relatives" is 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.

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.

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 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”. Here is a useful silkworm.

What do good intentions lead to?

Few people know that the 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.

Butterfly The silkworm is one of the most famous insects in the world. Initially, they appeared in the Himalayas and were wild, today this type of butterfly is considered a domesticated species. This process took place a very long time ago, around the third millennium BC.

Silkworm breeding is widespread. To do this, mechanized farms are created for the production of yarn, from which real silkworm silk is subsequently obtained.

Characteristics, habitat

These butterflies have become famous for their uniqueness. They weave cocoons, which in the future a person uses as a material for making real silk. The silkworm insect is directly related to the genus Silkworm. The silkworm belongs to the butterfly family.

As for the habitat, this is Asia, preferably the Southeast Territory, which has subtropical climatic conditions. You can rarely find such an insect on Far East, in places with approximately the same climate. In order to make silk, people have learned to breed insects in other regions, the only habitat condition is the presence of such a tree as mulberry, since the silkworm feeds only on it. The life span of such a butterfly is up to 12-13 days. And it will be interesting that such a butterfly does not fly, it simply does not know how to do it.

Such an insect looks completely inconspicuous and inconspicuous, even somewhat similar to an ordinary moth. The wingspan is approximately 2-3 centimeters. The color range ranges from gray to white-gray.

Life cycle

Despite many advantages, the silkworm is one of the most famous pests in the garden. It is not so easy to get rid of him, for any gardener the appearance of such a butterfly in the garden is by no means a joyful event, this is the beginning of a real disaster.

The life cycle of a silkworm butterfly consists of four stages and lasts approximately 2-2.5 months. The silkworm is a virtually immobile insect whose purpose in life is to lay eggs. The female insect can lay up to 650 pieces at a time. Egg laying takes about three to four days.

insect species

In nature, there are quite a few varieties of the silkworm insect. The most famous:

1. Silkworm nun - usually found in forests. The wings of this type of insect are black and white, dark gray, the whiskers have long notches. The breeding season is only summer period once every 12 months. For coniferous forest this caterpillar is unfavorable, causes significant harm, and this also applies to trees such as oak, birch, beech.
2. Ringed silkworm - this name was received because of the peculiar egg-shaped masonry. Debugs up to three hundred eggs at a time. The most terrible enemy for apple trees. By appearance light brown, dirty yellow butterfly covered with fluff. Specifically, the cocoons of this silkworm are used to make silk.
3. The pine silkworm is the main enemy of the pine, it can destroy the tree. The wings of this type of insect are dark brown, very similar to the color of the bark of pine trees. One of the largest in size large species butterflies. A female with a wingspan can reach a size of 10 centimeters, and a male - up to 7 centimeters.
4. The gypsy moth is one of the most dangerous pests in the world. Such an insect can destroy up to 3500 thousand plantings. This name was given to him due to the fact that the sizes of the female and male are too different.

diet

The main diet of the Silkworm consists of the leaves of the mulberry tree. The larvae that the female debugs have an insatiable appetite, so they eat a lot and grow too fast. The silkworm can also feed on figs, ficus leaves, milk tree and many other plantings. Those butterflies that are in captivity can also eat lettuce, which is very bad for their health and life cycle in general, and, accordingly, for offspring. To date, experts are developing a special universal food that will be suitable for all types of silkworms, both in freedom and in captivity.

Life cycle and reproduction

The mulberry silkworm, in terms of the method of reproduction, is no different from the method of reproduction of other butterflies. After the female debugs the eggs, the appearance of the first caterpillars should be expected within ten days. If the insect is in captivity and reproduction occurs not naturally, but artificially, a certain temperature of approximately 24-27 degrees must be observed. The silkworm butterfly caterpillar increases its appetite every day, and every day it needs more food.

On the sixth day of life, the insect larva freezes and stops eating, and the very next day, leaving the cocoon, it again begins to eat with great appetite. This is the so-called molt, in total there are four of them in the development cycle. The full development of the larva lasts about a month. Under the lower jaw of the insect, a so-called papilla is formed, which further releases a thread of silk.

Such a thread, although thin, can withstand weight up to 15-17 grams. This thread can be secreted not only by adult insects, but also by recently born larvae. The silkworm often uses such a feature in the form of a life jacket - if a threat arises, the caterpillar hangs calmly on its thread.

Caterpillar at the end life cycle takes a small amount of food, and during the construction of a cocoon refuses to eat at all. During such a period, the silk thread of the caterpillar is produced in excess, so it constantly reaches for it. Also during this period, the caterpillar behaves restlessly, constantly in search of favorable terrain for building its cocoon. Most often these are small branches. The entire construction of the cocoon takes approximately three to five days. The caterpillar uses about a kilometer of silk thread.

Very rarely in nature there are cases when silkworms weave one cocoon for several individuals up to about four at a time.

The weight of an ordinary silkworm cocoon can reach four grams, and in length - up to three centimeters. There are exceptions that reach six to seven centimeters.

The shape of the cocoon is not always the same, it happens:

• round;
• oval;
• ovoid;
• flattened.

The characteristic color is white, very rarely - golden, with a hint of green. The appearance of larvae occurs in three to four weeks. Since the jaw is still missing, a hole in the cocoon is made with the help of salivation, which dissolves the cocoon itself.

If such a process occurs under laboratory conditions, the insect pupae are killed, since the cocoon damaged by saliva is no longer valuable for obtaining silk raw materials. Some countries use these dead pupae as a culinary delicacy.

In itself, silkworm breeding is quite common, especially in Asian countries. Special farms are created there, which subsequently produce the desired silk thread.

Video: the birth of silkworm butterflies

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 pets and cultivated plants descended from wild species. Not without an insect on the farm - silkworm butterflies. For four and a half millennia of breeding work, it was possible to develop breeds that give silk different colors, and the length of a continuous thread from one cocoon can reach a kilometer! Butterfly has changed so much that now it's hard to tell who was her 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 of 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 other 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. According to 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. oral apparatus 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 mulberry leaves. 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 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.

This is the story of the little white butterfly that made famous Ancient China and made the whole world worship her great product.

Olga Timokhova, Candidate of Biological Sciences