- History of domestication
- Silkworm eggs and their incubation
- Caterpillars, molting
- Living in a cocoon
- Butterfly laying eggs
- Breeding
Various silk products have long become a common household item in human life. And the price of wonderful outfits was the prosaic and unsightly appearance of those creatures that create the finest threads of silk - silkworms. Looking at the photo of this adult creature, you can see a pale beige butterfly that cannot even fly. To compensate for this disadvantage, the silkworm has many beneficial properties, using which a person derives many benefits from them for his life.
History of domestication
The Himalayas are considered the homeland of these insects.
It is not known for certain when the properties of silkworms were studied by humans and used in their own farming. Some photos taken during archaeological excavations indicate that they tried to breed silkworms five thousand years ago. True, no one knows how successful it is. The first historical mention of these textile workers dates back to the seventh century BC. These manuscripts describe some of the details of silk production. Several centuries later, the silkworm becomes popular in Asia, where in China it becomes a kind of national treasure and strict checks are carried out to ensure that the caterpillars are exported outside the Middle Kingdom.
And yet, some cunning travelers managed to carry the cocoons in their canes, thereby destroying the Chinese monopoly on silk. Demand, of course, did not fall as a result, but Chinese traders simply had fewer tools for manipulation.
Silkworm food for gourmets
Few people know about the nutritional properties of the mulberry caterpillar. This is an ideal protein product and 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 that mold fungi are added to the “medicine”.
Silkworm eggs and their incubation
Today, the silkworm is a completely domesticated creature; its population in the wild has not been observed anywhere. Since silk mining has always been a very profitable business, today it is put into mass production.
The silkworm eggs from which the caterpillars hatch are placed in an incubator for eight to ten days. A set of silkworm eggs, which in scientific circles are called grenades, must be kept at sufficient humidity and temperature within twenty-three to twenty-five degrees Celsius for the entire incubation period.
Description
The silkworm is a relatively large butterfly with a wingspan of up to 60 mm. The body is quite massive, thick, covered with dense hairs. The wings are wide, well developed, off-white in color with brownish bands. Silkworm butterflies have almost lost their ability to fly. Females are especially inactive.
Caterpillars, molting
After the incubation period, small caterpillars are born, up to three millimeters in size. Such larvae are placed in special trays prepared specifically for this type of larvae, and kept in a well-ventilated, warm and moderately bright room.
And the silkworm breeders begin to carefully care for their pets. It is not for nothing that silkworms are called mulberry, since they feed on the leaves of the mulberry tree, which, undoubtedly, is also called mulberry in their honor. Young larvae have a very good appetite, so the amount of food needs to be almost doubled every day. So they continuously sharpen the leaves for five days.
And then they stop. You shouldn’t be afraid of this, it’s important to know that the time has come for the first molt. Old skin is stretched very tightly. One sharp jerk - and it bursts along the entire length of the body, and under it there is a new one, with some reserve of elasticity for even greater stretching.
During the entire period that the silkworm spends as a larva, which is just over a month, it molts four times. During this period, the caterpillar, painted light yellow, grows up to eight centimeters in length, and the thickness is slightly more than one centimeter.
By this time, the silkworm has a fully formed silk gland, the most valuable part for silkworm breeders, which reaches a size equal to two-fifths of the length of the larva. Now your silkworm will lose its appetite every day and stop feeding on its favorite mulberry leaves. And it’s not surprising, because the silk gland is filled with liquid, which is now released even when moving. It's time to climb into the cocoon.
How is silk obtained?
Real high-quality silk is obtained from the cocoons of silkworm caterpillars. And to get such beauty, some people have to try hard, which is why the price of natural silk is always high.
Why is silk so beautiful? Because the thread from which the silkworm spins a cocoon for itself, mulberry, has a unique triangular cross-section and, like a prism, refracts light, as a result we get a beautiful iridescence and shine.
The silk thread is 8 times thinner than a human hair, very durable, because it is designed to protect the caterpillars from hungry insects, and is absolutely water-repellent. Because of this, the fabric is soft and pleasant to the touch, but at the same time durable and wear-resistant. Silk fiber consists of 75% fibroin and 25% sericin. Waxes and fats are also present, as well as minerals. The width of the silk thread is approximately 32 microns, the length can reach one and a half kilometers.
Properties of silk fabric:
- It has average heat resistance - with prolonged exposure to high temperatures, the tensile strength decreases slightly, but the fabric becomes more fragile, the recommended temperature for wet-heat treatment is 110 degrees
- Very low light fastness - after just 200 hours of exposure to solar radiation, the strength is halved
- Silk, like other fabrics made from natural raw materials, is insensitive to the effects of organic solvents (vinegar, alcohol), and reacts only with concentrated solutions of acids and alkalis
- Has good hygroscopicity.
Living in a cocoon
When an adult caterpillar finds a suitable support, mainly a twig, it climbs onto it and makes the basis of a frame for its future location. Having weaved such a strong base, it crawls into its central part. Now begins the most difficult and time-consuming part of the work—making a full-fledged cocoon. The caterpillar turns its head at a fast speed, thereby entangling itself with thin silk threads and thus forming a cocoon within four days. The cocoon itself, oval or round in shape, reaches sizes of up to six centimeters. Having finished its work, the exhausted caterpillar falls asleep and awaits its reincarnation into a chrysalis.
An interesting feature: some silkworms do not weave cocoons, but form something like a flooring, into which they then crawl. Others form cocoons of several individuals, which becomes the subject of unusual photos of these unusual silkworms. But this is an exception to the rule, and not some peculiarity of silkworms.
Lifestyle and habitat
Nowadays, the mulberry butterfly exists only in artificial conditions. Its natural life can be reproduced from its supposed original species, the wild silkworm.
This butterfly lives in Eastern China on the Korean Peninsula. It is found where there are mulberry thickets, the leaves of which are the only component in the diet of silkworm caterpillars.
In one season, 2 generations develop. That is, the wild silkworm is bivoltine. The first generation of mulberry worms emerges from eggs in April-May. The second is at the end of summer. The butterfly season lasts from spring to late summer.
Butterflies do not feed; their task is to lay eggs. They do not migrate or migrate. Due to their attachment to territory and the reduction of mulberry thickets, entire populations of wild silkworms are disappearing.
Butterfly laying eggs
After three weeks, the silkworm pupa grows into a full-fledged butterfly, although it cannot fly. The butterfly is selected from its own woven cocoon by soaking the edges of its home with saliva, which is alkali in its chemical composition.
Because of this special saliva, the butterfly's mouth also softens and it is unable to feed. Perhaps this is the main reason for such a short subsequent life span, which lasts about two weeks.
During this time, you need to meet individuals of the opposite sex in order to fertilize the eggs. After just a few hours, silkworm eggs can be laid, which lasts five days.
Eggs in the amount of 300-800 pieces are laid in the grena, which sometimes has bizarre shapes, some of which are depicted in famous photographs. This depends on the timing of the caterpillar hatching, which can be carried out either this year or next.
Silkworm butterfly larvae
The larvae or eggs of this butterfly are scientifically called grena. They have a laterally flattened oval shape, with an elastic transparent film . The dimensions of one egg are so small that per gram of weight their number can reach two thousand.
Immediately after the butterfly lays its eggs, they have a light milky or yellowish color. As time passes, changes occur, leading to the appearance of a pink tint in the larvae, and then to a complete change in color to purple. If the color of the eggs does not change over time, it means the larvae have died.
Silkworm eggs have a fairly long maturation period. He lays them in the summer months: July and August, and then they hibernate until spring. The processes occurring in them at this time slow down significantly in order to survive the effects of low winter temperatures.
If the grena overwinters at temperatures not lower than +15 degrees, then there is a risk of poor development in future caterpillars, so in winter it is necessary optimal temperature conditions for the grena Caterpillars appear before leaves have time to grow on the trees, so grena is stored in refrigeration units at temperatures from 0 to -2 degrees throughout this period.
Breeding
The reason for breeding the silkworm is not to preserve its population, but to obtain raw silk for commercial use.
Therefore, many entrepreneurs are starting to engage in this profitable business. Since there are a sufficient number of silkworm breeders in our regions, you can ask them about the peculiarities of raising silkworms, and at the same time buy eggs. You just need to contact reliable suppliers of these products. Even small households can bring good profits to their owners.
Today in glossy magazines you can see photos of models dressed in silk clothes. Looking at this, you wonder how amazing the gifts of nature can be if you put enough effort and patience into their extraction, which in the end bears multiple fruits.
Nutrition
Only the silkworm caterpillar or the silkworm feeds. The diet is monotonous - mulberry leaves. The tree is universal. Its wood is used in carpentry. In Asia it is used to make folk musical instruments.
Despite the availability of food for silkworms, entomologists are constantly trying to find a replacement for mulberry leaves, at least temporarily. Scientists want to initiate early feeding of caterpillars and, in case of frost or death of mulberry plantings, have a backup option with food.
There has been some progress in finding a mulberry leaf substitute. First of all, it is a herbaceous plant called scorzonera. She throws out the first leaves already in April. When feeding caterpillars, scorzonera demonstrated its suitability: the caterpillars consumed it, and the quality of the thread did not deteriorate.
Dandelion, meadow goatweed and other plants showed satisfactory results. But their use is possible only in a temporary, irregular manner. With a subsequent return to mulberry. Otherwise, the quality of the final product noticeably deteriorates.
Corrosive woodworm and the fight against butterfly pests
- a large butterfly, the wingspan of which reaches 7 cm. Its white wings are covered with numerous blue-black spots.
Woodworm caterpillars are covered with hairs, which helps them spread over long distances with the wind.
The insect damages all fruit crops and many forest trees.
The laying of eggs by females continues until mid-August. Each of them is capable of depositing up to 1000 pieces in cracks in the bark and branching shoots.
The emerging caterpillars begin to damage young shoots of trees, biting into them. The leaves on such shoots dry out and die.
Caterpillars overwinter on tree branches and in passages made in them. Next season, the caterpillars have not yet become butterflies.
Only in the third season do the caterpillars gnaw exit holes, pupate inside the branch and then fly out.
In addition, you can stuff cotton balls soaked in gasoline into the passages made by the tree. After this, the entrance holes should be covered with clay.
From the beginning of August until the onset of leaf fall, it is recommended to periodically inspect the crowns of trees and remove young shoots damaged by woodworm.
When infested by corrosive woodworm caterpillars, it is recommended to spray the trees with a concentrated solution of chlorophos, but only after harvesting.
In this case, you should first spray only a few shoots of the tree to eliminate the possibility of burning the branches with concentrated chlorophos.
Types of caterpillars - photos and names.
Among the great variety of different caterpillars, the following varieties are of greatest interest:
The cabbage caterpillar or cabbage butterfly caterpillar (cabbage white butterfly) (lat. Pieris brassicae) lives throughout Eastern Europe, northern Africa to the Japanese islands, and was also introduced to South America. The caterpillar is 3.5 cm long, has 16 legs and has a light green body covered with black warts and short black hairs. Depending on the weather, the caterpillar stage lasts from 13 to 38 days. These caterpillars feed on cabbage, horseradish, radishes, turnips, turnips and shepherd's purse. They are considered the main pest of cabbage.
The moth (land surveyor) caterpillar (lat. Geometridae) is characterized by a long thin body and undeveloped abdominal legs, due to which it has an original method of movement - it bends in a loop, while pulling the abdominal legs to the pectoral legs. The family includes more than 23 thousand species of moths distributed throughout the world. All types of caterpillars of this family have well-developed muscles, and therefore are able to attach themselves vertically to plants, perfectly imitating broken branches and petioles. The color of the caterpillars is similar to the color of foliage or bark, which additionally serves as an excellent camouflage. They eat tree needles, currants and hazel.
The great harpy caterpillar (lat. Cerura vinula = Dicranura vinula) lives throughout Europe, Central Asia and northern Africa. Adult caterpillars grow up to 6 cm and are distinguished by a green body with a purple diamond on the back, bordered by a white outline. In case of danger, the caterpillar inflates, takes a threatening pose and sprays out a caustic substance. The insect remains in the caterpillar stage from early summer to September, feeding on the leaves of plants from the willow and poplar families, including the common aspen.
The red-tailed caterpillar (lat. Calliteara pudibunda) is found in the forest-steppe zone throughout Eurasia, as well as in Asia Minor and Central Asia. The caterpillar, up to 5 cm long, is pinkish, brown or gray in color. The body is densely covered with individual hairs or tufts of hair, at the end there is a tail of protruding crimson-colored hairs. This is a poisonous caterpillar: upon contact with human skin, it causes a painful allergy. These caterpillars eat the foliage of various trees and shrubs, especially preferring hops.
Silkworm caterpillar (lat. Bombyx mori) or silkworm. Lives in East Asia: in northern China and Russia, in the southern regions of Primorye. The caterpillar is 6-7 cm long, its wavy body is densely covered with blue and brown hairy warts. After 4 molts, completing the 32-day development cycle, the color of the caterpillar becomes yellow. The food of the silkworm caterpillar is exclusively mulberry leaves. This insect has been actively used in sericulture since the 27th century BC. e.
Caterpillar of the corrosive woodworm (lat. Zeuzera pyrina) from the woodworm family. It is found in all European countries except the Far North, as well as in South Africa, Southeast Asia and North America. It overwinters twice, during which time it changes color from yellow-pink to yellow-orange with black, glossy warts. The length of the insect is 5-6 cm. Caterpillars live inside the branches and trunks of various trees, feeding on their juices.
The caterpillar of the lady bear (lat. Callimorpha dominula) or girl bear lives in Eastern and Western Europe and in southeast Asia. It overwinters once and is distinguished by its black and blue color with yellow stripes and spots. Lives on nettles, geraniums, willows, raspberries, strawberries, and feeds on them.
The swallowtail caterpillar (lat. Papilio machaon) lives throughout Europe, Asia, northern Africa and North America. One of the most colorful caterpillars: at first black, with scarlet warts, and as it grows it becomes green with black transverse stripes. Each stripe contains 6-8 red-orange spots. The disturbed caterpillar secretes an odorous orange-yellow liquid. It feeds on carrots, celery, wormwood, parsley, and sometimes alder leaves.
The smallest caterpillar in the world is a member of the moth family. For example, clothes moth caterpillars (lat. Tineola bisselliella), which have just emerged from eggs, reach a length of only 1 mm.
The largest caterpillar in the world is the Atlas peacock caterpillar (lat. Attacus atlas). The bluish-green caterpillar, as if dusted with white dust, grows up to 12 cm in length.
