Silkworm: interesting facts and photos. Mulberry silkworm or how real silk is made Silkworm characteristic

The history of breeding such an insect as the silkworm is extremely interesting. 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 cocoons silkworm found by archaeologists date back to 2000 BC. e. The Chinese elevated silk making to the status of a state secret, and for many centuries this was the country's clear priority.

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

Silkworm butterfly and its offspring

The domesticated silkworm butterfly is not found today in wild nature and is bred in special factories to obtain a natural thread. An adult is a fairly large light-colored insect, reaching 6 cm in length with a wingspan of up to 5-6 cm. various breeds 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. Many breeds of silkworm have been bred. Some give one generation a year, others two, and there are species that give several broods a year.

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

Caterpillar - the next stage of development

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

Moult

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

caterpillar transformations

For the entire period of development (about a month), the caterpillar molts four times. The last molt turns it into a 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. It 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.

The formation of a silk thread

This tubercle ends with two silk glands, which are long tubes with a middle part turned into a kind of reservoir in the body of the caterpillar, accumulating a sticky substance, which subsequently forms a silk thread. If necessary, the caterpillar releases a trickle of liquid through the hole under the lower lip, which solidifies and turns into a thin, but strong enough thread. The 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 twist the actual cocoon.

Cocoon and pupation

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

The weight of the cocoon together with the pupa 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.

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.

The silkworm is a nondescript butterfly from the family of real silkworms, a detachment of mulberries. The insect was domesticated in China more than 3 thousand years ago, plays an important economic role in the production of natural silk, sericulture. In nature, there is a wild silkworm, which is considered a "derivative" of the domestic one. Dwells in East Asia, China, Primorsky Krai of Russia.

Appearance of a moth

The silkworm butterfly is rather large in size. The wingspan is 60 mm. The color is off-white with brown streaks. The body is divided into segments, on the head there are hairy comb antennae in males, less pronounced in females. Despite the significant size of the wings, the silkworm butterfly practically does not fly, leads a sedentary lifestyle due to domestication. The oral apparatus is underdeveloped, throughout adult life the insect does not feed.

Interesting!

The wild silkworm moth is quite beautiful, the color is close to white. Slightly smaller in size. At home, hybrids are bred for industrial purposes with different colors- pink, brown, brown. There is also a stripless silkworm. However, the white moth is more valued.

A photo of the silkworm is presented below. You can take a close look at the features appearance butterflies male, female. includes several stages:

• egg;
• larva;
• chrysalis;
• imago.

The duration of development depends directly on the conditions environment, availability of food.

Eggs

After fertilization, the female lays from 500 to 700 eggs - grain. The shape is oval, elongated, flattened on the sides. The size of one egg does not exceed 1 mm in length, 0.5 mm in width. On the one hand, along the length of the grain, there is a recess, on the other, a bulge. The color is off-white, milky, yellowish immediately after laying, purple towards the end of maturation of the larva. If the color scheme does not change, this means the death of the embryo inside.

The ripening period of grains is long, with a decrease in temperature, metabolic processes slow down, development stops. The female lays eggs in July-August. Development continues in early spring when the eggs hatch into larvae. At a constant high temperature more than +15 degrees Celsius larvae may appear in the same year.

Interesting!

Home silkworm eggs are placed in the refrigerator, where the temperature is maintained from 0 to -2 degrees Celsius. Under such conditions, a strong, healthy silkworm caterpillar appears in spring. If the wintering temperature is higher, the younger generation is born weak. This is due to the fact that the caterpillar appears too early, when there is not yet enough food for it.

Larva

The silkworm caterpillar resembles white worm before they were called that. The body is elongated with a head, abdomen, chest. On the head are small horns - appendages. On the inside of the body there are 8 pairs of legs, with the help of which the silkworm larva moves along the tree bark and leaves. The chitinous cover is quite dense, it performs the function of muscles. A photo of a silkworm caterpillar can be seen below.

Larvae appear extremely small, no more than 1 mm in length, but with a good appetite. exclusively with mulberry leaves, it is also a mulberry tree, which is why the name of the insect came about.

The full cycle of caterpillar development is 45 days. During this time, 4 molts occur. Before last stage the caterpillar increases in size up to 30 times. In conclusion, the caterpillar forms a cocoon of silk thread around itself, for the sake of which insects are grown. If you unfold one cocoon, you get the length of the thread from 300 to 1600 m.

Interesting!

Pupa of a silkworm of snow-white color. A butterfly develops inside for several days, independently gets out. Shortly before this, you can hear the noise, feel the movement in the cocoon.

The appearance of the imago

The formed silkworm moth secretes a special sticky substance that can dissolve the cover of the chrysalis, threads. The head is shown first, then the wings. For its birth, the butterfly chooses the time from 5 to 6 in the morning.

Within a few hours after birth, the mating process begins. The butterfly lives for about 20 days, but there are also centenarians who live up to 45 days. The male lives half as much. Butterfly does not eat anything, only reproduces the younger generation. Even being headless, the female does not stop this process.

The silkworm is grown specifically to produce silk threads, a person regulates the number of insects on his own. To obtain raw materials, moths are not allowed to be born, a cocoon is placed in conditions unfavorable for the development of adults.

On a note!

The silkworm does not harm a person, they do not fight with it, they specially create favorable conditions for nutrition and development. But it is a real pest, with which an intense struggle is being waged. The insect damages about 300 varieties of deciduous, coniferous plants. Keeps up with the unpaired, destroying any coniferous trees within its range.

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 have been able to enjoy outfits made of beautiful soft fabrics for more than 5000 years, 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, an immediate and terrible death penalty was due. 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 silkworm breeds in the world. 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 mouth apparatus, so it does not feed throughout its entire life. 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 emerge from the cocoon on the 15-18th 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 set out on a perilous journey and returned the same year with 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 silkworms have been bred quite successfully in the Po Valley. In the XIV century. sericulture began in the south of France. And in 1596, silkworms were first bred in Russia - first near Moscow, in the village of Izmailovo, and over time - in the more suitable southern provinces of the empire.

However, even after the Europeans learned to breed silkworms and unwind cocoons, most of the silk continued to be delivered from China. For a long time, this material was worth its weight in gold and was available only to the rich. Only in the 20th century, artificial silk somewhat pressed natural silk on the market, and even then, I think, not for long - after all, the properties of natural silk are truly unique.
Silk fabrics are incredibly durable and last a very long time. Silk is lightweight and retains heat well. Finally, natural silk very beautiful and lends itself to uniform coloring.

Used sources.