Silkworm habitat. Features, characteristics, reproduction and why does a person need a silkworm? Silkworm and man

Butterflies, thanks to which people have the opportunity to wear silk things, appeared on the planet a long time ago. Back in the fifth millennium BC new era Silkworm cocoons were used by people.

The wild silkworm, without knowing it, played a big role in the history of states ancient world. You can learn about this from the video.

Nowadays, the range of insect uses is very wide. Fried larvae and pupae are considered a delicacy in Korea. delicious dish, which they rush to feed guests, although Europeans do not consider them a delicacy. The larvae contain a large number of protein, which is why they are so popular among gourmets.

In addition, larvae are used to obtain medicines, in cosmetology, medicine, and the list goes on.

The leaders in silk production are India and China; the mulberry tree is found almost everywhere here, so the silkworm has all the conditions for its growth. Unfortunately, there are many more silk connoisseurs than those who are interested in this inconspicuous, but very hardworking insect.

Let's look at the features, characteristics of the insect, the reproduction process and try to answer the question - what role does the silkworm play in human life.

What does an insect look like?

The mulberry tree, or mulberry, is the only habitat for the silkworm. Caterpillars are so voracious that a tree can be left without leaves in one night, so gardening farms pay special attention to preserving trees from insect invasion. Silkworm breeding enterprises are always surrounded by hectares of mulberry plantations. On an industrial scale, this tree is grown in compliance with all norms and requirements in order to provide the insects with adequate nutrition.

We owe the appearance of silk to caterpillars and butterflies, but to understand how an insect lives, we need to consider the entire process of its development.

The life cycle of an insect consists of the following stages:

• adult moths mate, after which the female lays many small eggs (larvae);
• small dark caterpillars emerge from the eggs;
• the caterpillar lives on the mulberry tree, eats its leaves and grows quickly;
• caterpillars create silkworm cocoons, after a while the caterpillar finds itself in the center of a cocoon of silk threads;
• a pupa appears inside a skein of thread;
• the pupa becomes a moth that flies out of the cocoon.

This process is interesting and continuous, like many other natural cycles.

You can learn interesting facts from the life of an ancient insect, which for many centuries was equal in value to gold, by watching the video.

The butterfly is white, with dark spots on the wings, large, its wingspan is 6 centimeters. In females the mustache is almost invisible, in males it is larger.

Ability to fly for long years the butterflies have lost, and besides, they can easily do without food. They have become so “lazy” thanks to man that their life is unthinkable without human care and care. Caterpillars, for example, are unable to find their own food.

Varieties of silkworm

Modern science knows two types of silkworms.

The first type is called monovoltine . The larvae appear only once.

The second type is called multivoltine. More than one offspring appears.
Butterfly

Hybrids have external differences. They differ in the color of the wings, the shape of the body, the size of the pupa and butterflies. Caterpillars also have different colors and sizes. The possibilities of genetics have no limits; there is even a breed of silkworm with striped caterpillars.

What indicators are used to determine productivity?

Productivity indicators are:

• number of cocoons, mostly dry;
• do they unwind easily?
• how much silk can be obtained from them;
• quality and other characteristics of silk threads.

Caterpillar

Let's talk about green

Grena is nothing more than silkworm eggs. They are small and have oval shape, slightly flattened on the sides, covered with an elastic shell. The color of the grena changes from light yellow to dark purple; if the color does not change, this indicates that they have lost their vitality.

Grena takes a long time to ripen, somewhere from mid-summer until spring. In winter, metabolic processes occur much slower, which allows her to survive the winter safely. The caterpillar should not hatch ahead of schedule, otherwise, due to the lack of mulberry leaves, it is in danger of death. Eggs can overwinter in the refrigerator, at temperatures from 0 to -2C.

Grena

Meet the silkworm caterpillar

Caterpillars, or as they were previously called, silk worms (photo below) look like this:

• elongated, like all worms, body;
• the head, abdomen and chest are clearly defined;
• small horns on the head;
• chitinous covers protect the body and are muscles.

Silkworm caterpillar

The caterpillar appears small, but viable, its appetite grows, so its size quickly increases. She eats around the clock, even at night. Walking near mulberry trees, you can hear a peculiar rustling sound - this is the work of the small jaws of voracious caterpillars. But their weight is not constant, because they lose it four times in their lives. A huge number of muscles allows the caterpillars to demonstrate real acrobatic tricks.

Watch the video and see for yourself.

In forty days, the body of the caterpillars increases significantly, they stop eating and molt, clinging to the leaf with their paws, they become motionless.

Photo of a caterpillar sleeping. Touching the caterpillar can interfere with the natural cycle and it will die, so you should not touch them. By molting four times, they change color four times. Silk is produced in the silk gland of caterpillars.

There was a chrysalis, and a butterfly appeared

It does not take much time for the cocoons to form. The caterpillar flies out of it like a butterfly. After molting, the caterpillar becomes a pupa, after which it becomes a butterfly.

You can learn how caterpillars turn into butterflies from the video.

Before the butterfly flies, the cocoons begin to move, a slight noise is heard inside, this is the rustling of the pupa’s skin, which the butterfly has no use for. They appear only in the morning hours - from five to six in the morning. Using a special adhesive substance, they dissolve part of the cocoon and get out of it.

No one considers them beauties, which cannot be said about their domestic relatives.

Butterflies have a short life - no more than 20 days, but sometimes they live for a whole month. Mating and laying eggs are their main occupation; they neglect food, since they do not have the opportunity to absorb and digest food. But there is no doubt about the strength of gluing of grain to a tree or leaf.

That's all short life a worker - a silkworm, which has been beneficial to humans for almost five thousand years.

Information for the curious!

• In addition to the fact that the insect cannot fly, it is also blind.
• It only takes three to four days to create a cocoon, but during this time a silk thread 600-900 meters long is obtained. There are known cases when the unwinding thread was 1500 meters long. In terms of strength, a silk thread can be compared with steel, their diameter is the same, and it is not so easy to break the thread.
• The quality of a silk product can be assessed by its color; the lighter it is, the better the quality. Silk items cannot be bleached.
• Moths and mites, which can ruin clothes, do not pose a threat to silk fabrics. And the explanation for this is a substance that is in insect saliva, it is called sericin. To this we should add that silk has another advantage - its hypoallergenic properties. Elastic and durable threads have found application not only in the textile industry. They are used in medicine, aviation and aeronautics.

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 material, amazing in quality, is produced by unsightly-looking caterpillars, which, eating the leaves of the mulberry tree (for us, the name mulberry is more familiar), process them, creating an amazingly 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 the silkworm" or "dead silk." This tragic name is explained by the fact that a living butterfly is deliberately not allowed to leave the cocoon, so the insect, suffocating, dies inside it (more about this sad fact a little lower in the text).

Cocoons can be of various colors and shades, which depends primarily on the type of silkworm, but white color is considered the highest in quality, since 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 descended from its wild relative, which previously lived in mulberry thickets 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).

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

Egg

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

Silkworm embryos are small and light yellow or milky in color. Having laid from three hundred to six hundred eggs (sometimes the number of eggs in the egg laying 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, happily eating juicy mulberry leaves.

Silkworm caterpillars are very sensitive to temperature and humidity, are intolerant of strong odors and cannot tolerate loud sounds, but if external conditions habitats are quite favorable, the larvae sharply gain weight, day after day, increasing their consumption rate plant food. In the rooms where silkworms are raised, there is a continuous hum from the monotonous work of many jaws, as if light rain drumming on the metal roof.

It’s hard to imagine that these babies have more than four thousand muscles in their tiny bodies, which is eight times (!) more than a human’s.

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 day of birth, while the caterpillar stops feeding, and, tightly clinging to the leaf, hibernates for a day. Having woken up, the caterpillar sharply straightens its body, causing the old skin to burst and the grown insect, freed from its previous clothes, with new strength pounces on food.

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

Doll

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.

Ninety percent of the silkworm thread consists of protein. In addition, it contains salts, fats, wax and adhesive substances. sericin, which prevents the threads from falling apart, tightly fastening them to each other.

When the time comes, the caterpillar attaches its body to 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 to 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 carefully, 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 untwisted to obtain a thread of unique quality. If this process is late, then an adult insect will emerge from it ( imago) in the form of a butterfly, which will damage the shell of the cocoon and the thread will end up torn.

As mentioned earlier, the butterfly has an underdeveloped oral 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 top part cocoon, damaging the threads. To avoid this, butterflies are artificially killed directly in cocoons using hot air, treating the pupae for two hours. This process kills the butterfly, so that the name of this insect species (" Death of the Silkworm") completely justifies itself.

After unwinding the thread, the dead pupa is eaten (usually in China and Korea) as it is rich in protein and nutrients.

The process of creating silk thread

Currently, silkworms are mainly raised artificially.

The cocoons are collected, sorted by color, size and prepared for subsequent unwinding, for which they are dipped into boiling water. This process is still done by hand, since the cocoon thread 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 tie all the ends together.

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

Legend has it that the first person who came up with the idea of ​​weaving yarn from silk thread was the legendary Chinese Empress Lei Zu (also known as Xi Lingshi), walking through 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, causing the cocoon to unwind.

Lei Zu convinced her husband (the legendary ruler of China Huang Di 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 the invention of a special spool that combines thin threads into one strong thread suitable for weaving, and the invention of the silk loom.

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

People know a lot about the benefits of silk, but few people know the “creator” who gave this miracle to the world. Meet the mulberry 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 pupa located in a silk cocoon.
• Butterfly.

As soon as the caterpillar's head darkens, the lenching process begins. Usually the insect sheds its skin four times, the body becomes yellow, and the skin becomes dense. So the caterpillar moves to a new stage, becoming a pupa, which is located in a silk cocoon. IN natural conditions the butterfly gnaws a hole in the cocoon and squirms out of it. But in sericulture, the process follows a different scenario. Manufacturers do not allow silkworm cocoons to “ripen” until the last stage. Within two hours of exposure high temperature (100 degrees), the caterpillar then dies.

Appearance of a wild silkworm

Butterfly with large wings. Domesticated silkworms are not very attractive (the color is white with dirty spots). It is radically different from its “domestic relatives”; it 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, produces 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 it is not capable of getting food on its own.

Useful properties of silk thread

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

To feed thirty thousand caterpillars you will need a ton of mulberry leaves, 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 silk cocoon threads can exceed 1 km. Now imagine how much work a silkworm needs to do 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 matting substances of sheer origin (silk glue) from which it weaves a silk thread. Despite the fact that most of this substance is lost during the manufacturing process of silk fabric, the little that remains in the silk fibers can protect 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 the silk threads have been removed. Empty cocoons are used in cosmetology. They are used to prepare masks and lotions not only in professional circles, but also at home.

Silkworm food for gourmets

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


In Korea, half-raw silkworms are eaten and lightly fried. This is a good source of protein.

Dried caterpillars are commonly used in Chinese and Tibetan folk medicine. The most interesting thing is what they add to the “medicine” molds. This is how useful the silkworm is.

What good intentions lead to

Few people know that the gypsy moth, which is a major pest of the US forestry industry, was spread as a result of a failed experiment. As they say, I wanted the best, but what happened was the following.

This insect is one of the few domesticated by humans.

The amazingly beautiful fabrics obtained from the fiber it produces have been pleasing to the eye for many centuries.

What is it - silkworm - life cycle and insect nutrition will help you understand all the secrets of making Chinese silk, which have been kept for thousands of years.

According to various sources, it is from 7000 to 5000 years old. Now it is impossible to say who first came up with the idea of ​​unwinding the cocoon and making fabric from the resulting thread.

But what is certain is that for a long time the secret of its manufacture was a state secret.

Even for trying to disclose it, they simply cut off their heads. But gradually the secret was revealed, and already in the Middle Ages, all wealthy European nobility sported silk outfits produced in Venice and Florence, Genoa and Milan. And at the end of the 18th century, silk was already woven throughout Europe.

Silkworms were domesticated more than 2,000 years ago. For such long term the insect has become completely dependent on humans and simply cannot exist without them.

Even domestic bees can live quite well in wildlife, and the silkworm will simply die under these conditions. Butterflies have practically forgotten how to fly, and caterpillars have almost forgotten how to hide from enemies.

Without constant feeding of mulberry leaves, which is provided by humans, they will simply die. Their living space has not been in nature for a long time.

The entire cycle of existence takes place in closed rooms specially equipped for this purpose. During its long existence next to humans, many breeds of this insect were created.

They were selected based on the following criteria:

• color and shape;
• cocoon structure;
• size and color of caterpillars;
• cocoon yield;
• their silkiness;
• quality of silk.

Currently, hybrids have appeared that are more resilient.

Features of the silkworm

The insect belongs to the family of true silkworms. In the wild it lives in countries East Asia, namely, in the north of China and the south of Primorsky Krai.

Depending on the breed of the bred insect, the following types are distinguished:

1. monovoltine - they are capable of producing only one generation per year;
2. bivoltine - breed twice a year;
3. multivoltine - produce several generations per year.

In the wild, the silkworm winters during the egg stage. They enter a kind of resting period called diapause.

The metabolism in the embryo slows down, which allows it to survive until spring without problems in order to hatch by the time food becomes available.

A streamlined industrial production process allows caterpillars to be fed throughout the year.

The production of silkworm caterpillars occurs wherever natural silk is woven.

Silk fabric production

In China and neighboring Korea they are used to prepare unusual dishes and produce medicines used in folk medicine.

Not everyone is lucky enough to see an insect in person at all stages of development. To have an idea about this, let’s look at what the silkworm looks like.

Appearance

An adult insect is a butterfly whose wingspan can reach up to 6 cm.

Open wings of a silkworm

They are off-white with fairly distinct brownish bandages. The butterfly has a powerful, pubescent body, divided into segments.

Males and females can be distinguished by their antennae. The former have pronounced scallops. Appearance and coloring can vary greatly depending on the breed.

Life cycle stages and reproduction

This insect undergoes a complete transformation throughout its life.

The life cycle of the silkworm consists of the following stages:

• egg;
• caterpillar larva;
• cocoon pupa;
• imago.

Egg

The eggs of the silkworm, which silkworm breeders call grena, are extremely small—up to 2,000 eggs can be counted in one gram.

Their color changes with the age of the grenade: from yellow or milky white to violet-ash.

Dead grena does not change color. The eggs are oval in shape, the outer shell is elastic and translucent.

Having mated, the female immediately lays eggs, which can contain from 400 to 1000 eggs.

Silkworm eggs

Interestingly, a butterfly can lay eggs even if it has no head: nervous system autonomous in every segment of the body.

Females are very caring; for better development, each egg is firmly glued to the surface on which it is laid.

Caterpillar or larva

Its silkworm breeders usually call it a silkworm; its body is elongated with three pairs of thoracic and five pairs of abdominal legs. The weight of a newly hatched caterpillar is only 0.5 mg.

Silkworm caterpillars

Thanks to a good appetite, in 20-38 days, which is how long the development of the silkworm in the larval stage lasts, it increases its weight by 10,000 times and its size by 30 times.

During their growth, silkworm larvae change their skin 4 times and become increasingly lighter. The mass of the silk gland also increases.

It is in it that silk is formed and a silk thread is formed. It takes a lot of it to create a cocoon. According to various sources, the length of the silkworm thread can reach from 1500 to 3000 m.

A comfortable temperature for caterpillar development is from 21 to 23 degrees Celsius, and air humidity is in the range of 60-70%.

Doll

To provide it with protection, the caterpillar weaves a cocoon from silk produced by the silk gland.

The pupa stays in it for 15 to 18 days. The day before the butterfly emerges, the cocoon begins to move.

All butterflies emerge at the same time: from 5 to 6 am. Before leaving they release a few drops special liquids, capable of dissolving sericin, which glues the cocoon threads together to make a hole for exit.

Silkworm cocoons can have different colour: pinkish, greenish, yellow.

Silkworm cocoon and pupa

To make silk you need white threads. Therefore, for industrial breeding, those breeds of silkworms with white cocoons are used.

By their size you can judge what gender the butterfly will hatch: in the female they are slightly larger and heavier.

Lifespan

Adults do not live long, on average about 12 days. Only some centenarians increase this period to 25 days.

Such a short life span is due to dietary habits.

Nutrition

In adult butterflies, the oral apparatus is not developed, so they do not feed at all, but the caterpillars chew around the clock.

Different stages of silkworm development at the larval stage require food of different fractions. The first instar larvae have to grind it.

Silkworm caterpillar eating foliage

In the future, you can switch to whole leaves. The number of feedings in the first and fourth instars is 10, in the second and third instars - 8, in the fifth instars - 18. But in any case, only mulberry foliage can become the basis of nutrition.

The silkworm is a monophage and is not capable of feeding on anything else. Where silk production is established, there are always large mulberry groves. They are specially planted to feed the larvae.

Conclusion

This amazing insect For more than one thousand years, it has been enabling man to produce beautiful fabrics.

The technology for their production and breeding of insects has been brought to perfection during this time.

And this was helped by knowledge of the biology of the insect, its lifestyle, development cycle and feeding method.

Video: Animals in history. Silkworm

China is an amazing country filled with myths and legends. According to one of the ancient legends, the wife of the mythical Yellow Emperor taught her people to weave and extract silk from the silkworm. How much you can believe this legend is unknown, but to this day China is breeding this butterfly.

What does it look like

This is a fairly large butterfly with a wingspan of up to 60 mm, which has unique individual characteristics. For example, in the process of evolution and domestication, it lost its ability to feed and acquired.

After emergence, she mates, lays larvae and dies. Its ancestors ate the leaves of the mulberry tree; it was in its crown that they lived, which is why the name of this insect came about.

Lifestyle

It has been noted that males, when spinning a cocoon from a single silk thread, spend a little more vital resource and time on this. As a result, the male’s cocoon turns out to be 25% heavier than that of the female. The process of creating a silk cocoon is very labor-intensive and troublesome, releasing lower lip two strong, but at the same time the thinnest threads, the caterpillar weaves its house for 18-25 days to transform into a butterfly.

An important point In the life of the silkworm, it serves to arrange a place for hammering: thin rods must be installed in it, and it is in them that the silkworm will weave its house. The size of the cocoon reaches 38 mm, it is very dense with closed edges.

Reproduction

The life cycle of an insect is simple and primitive, and over many years of work with it by humans, it has been refined into a mechanism.
After mating, the female spends 2-3 days laying eggs; she produces about 600 eggs per clutch. After the appearance of a tiny caterpillar and with proper maintenance, it will grow and develop for about 25 days until it reaches maturity. And only then will preparations begin for transformation into a butterfly.

The pupa becomes a pupa on the 10th day, and only then can silk cocoons be used to produce silk thread.

Economic importance

Today you can go to silkworm breeding factories, see and learn the entire production process, but several centuries ago for the Chinese, everything related to the production of silk from silkworms was a closely guarded secret, the disclosure of which was threatened the death penalty. But there are no secrets that cannot be revealed. The same thing happened in this case. Gradually, cunning traders revealed this secret, and it became the property of many nations. Silk production began to develop in India, Europe, Russia, and Kazakhstan.

The silkworm is a worker in the textile industry.

The second country where they started doing this profitable business, based on the reproduction of butterfly larvae, India became. Today it occupies a leading position in the production of natural silk.

The silkworm is no longer found in the wild, and its entire life cycle takes place under human supervision.

Modern developments make it possible to select the silkworm to such an extent that the cocoon itself has whitest color. Cocoons of gray, green or yellow color are not suitable for producing high-quality silk, so breeders do not use them in large-scale production.