Silkworm

“ Diseases.—That the silkworm is subject to many serious diseases is only to be expected of a creature which for upwards of 4000 years has been propagated under purely artificial conditions, and these most frequently of a very insanitary nature, and where, not the healthy life of the insect, but the amount of silk it could be made to yield, was the object of the cultivator. ”

“ The common silkworm produces as a rule only one generation during the year; but there are races in cultivation which are bivoltine, or two- generationed, and some are multivoltine. Its natural food is the leaves of mulberry trees. The silk glands or vessels consist of two long thick-walled sacs running along the sides of the body, which open by a common orifice—the spinneret or seripositor—on the under lip of the larva. ”

“ As the Silkworm is an insect of universal service, and not of singular beauty, we are induced to prefer giving an account of its utility, rather than any elaborate description of its figure or colour. ”

“ As the silkworm spins its web by thus bending the fore part of the body back, and moves the hinder part of the body in such a way only as to enable it to reach the farther back with the fore part, it follows that it encloses itself in a cocoon much shorter than its own body, for soon after the beginning the whole is continued with the body in a bent position. ”

“ There is scarce anything among the various wonders which the animal creation affords more admirable than the variety of changes which the silkworm undergoes; but the curious texture of that silken covering with which it surrounds itself 52when it becomes a moth, and arrives at the perfection of its animal life, vastly surpasses what is made by other animals of this class. All the caterpillar kind do indeed undergo changes like those of the silkworm, and the beauty of many of them in their butterfly state greatly exceeds it ”

“ A silkworm establishment was pointed out to us in the distance, but we did not go over it, as we had seen many before, and it is not the best season of the year. The silkworms are most carefully tended, the people who look after them being obliged to change their clothes before entering the rooms where they are kept, and to perform all sorts of superstitious ceremonies at every stage of the insect's growth. No one at all ailing or deformed is allowed to approach a building where they are kept. ”

“ The rearing and management of silkworms is an innocent and agreeable pastime both to boys and girls, and it is very interesting in many points of view. One fact is, that while the caterpillars of all the other tribes of moths and butterflies, when they have arrived at a certain state of maturity, show a restless disposition, and wander about and hide themselves in a variety of places in order to spin their cocoons, the silkworm, on the contrary, is content to remain stationary in the open tray or box in which it may be placed. ”

“ When full grown the Silkworm commences spinning its web in some convenient spot, and as it does not change the position of the hinder portions of its body much, but continues drawing its thread from various points, and attaching it to others, it follows that after a time its body becomes, in a great measure, enclosed by the thread. ”

“ In this part of the work we notice the most perfect adaptation of the creature to the needs of man. While the silk threads from the cocoons of other species which might prove of value cannot be easily reeled off, those of the silkworm, when placed in hot water, readily separate, and can be gathered in a condition for spinning. Thus, while some success has been attained by carding the cocoons of other species, thereby making a fibre which has a certain utility, the silkworm alone yields material fitted for delicate fabrics. ”

“ The life-history of the silkworm is a wonderful illustration of the devious ways in which nature does her work. The silkworm moth, which belongs to the family of bombici, lays thousands of eggs, and dies soon after fulfilling this function. Incubation is fostered by Italian and other continental silk-farmers by means of carefully regulated incubators, and before the eggs are selected a microscopic examination is made of the moths for the purpose of eliminating eggs laid by diseased moths. ”

“ You are entitled to this exhibition, for, without your constant care and feeding, these creatures would not have been able to develop. The dull, inactive silkworm has acquired wonderful agility, and without practice is able to weave himself into his sleeping bag with astonishing celerity, reeling out his twelve hundred or sixteen hundred yards of silk in one continuous thread. ”

“ This is, however, not the only purpose for which man has designedly introduced foreign forms of insect life. The eggs of the silkworm are known to have been brought from the farther East to Europe in the sixth century, and new silk-spinners which feed on the castor-oil bean and the ailanthus, have recently been reared in France and in South America with promising success. [Footnote: The silkworm which feeds on the ailanthus has naturalized itself in the United States, but also the promises of its utility have not been realized.] ”

“ Millions of cocoons of the Tusseh silkworm are annually collected in the jungle, and brought to the silk factories near Calcutta. In other parts the people gather and transplant them to the trees near their own dwellings, that they may watch over the safety of the caterpillars, which are very liable to be devoured by crows during the day time, and by bats at night.
The Arindy silkworm feeds only on the leaves of the Palmi Christi; it produces so delicate and flossy a silk that it cannot be wound from the cocoons ”

“ A silkworm, while it is a worm, feeds to repletion,—you can never get it as many mulberry leaves as it would like to eat—then when it is gorged, it builds itself a beautiful house of silk (which is taken away from it in due course) and comes out at the door in wings!—wings it hardly uses and seems not to understand—then, if it is a female moth, it looks about for 'love' from the male. If the male 'loves' it, the female produces a considerable number of eggs like pin-heads—and then?—what then? Why she promptly dies, and there's an end of her! ”

“ The supply of waste silk is drawn from the following sources: (1) The silkworm, when commencing to spin, emits a dull, lustreless and uneven thread with which it suspends itself to the twigs and leaves of the tree upon which it has been feeding, or to the straws provided for it by attendants in the worm-rearing establishments: this first thread is unreelable, and, moreover, is often mixed with straw, leaves and twigs. (2) The outside layers of the true cocoon are too coarse and uneven for reeling ”

“ Once that is out of the way, the silk can be wound on a card. The moth soon afterward appears and, after growing to its full size, lays its eggs—some two hundred—and dies. It must be remembered that with silkworms a little practical demonstration from any one who has kept them is worth much more than many pages of hints. One thing is of the highest importance, and that is constant attention. ”

“ The forepart of the old skin is burst; the Silkworm then, by continually writhing its body, contrives to thrust the skin back to the tail and disengage itself; this is difficult, however, since it is no uncommon occurrence for them to die from not being able to free themselves. ”

“ Pasteur had come to regenerate the Silkworm, while knowing nothing about caterpillars, cocoons, chrysalids or metamorphoses. The ancient gymnasts came naked to the fight. The talented combatant of the plague of our Silk-worm-nurseries hastened to the battle likewise naked, that is to say, destitute of the simplest notions about the insect which he was to deliver from danger. ”

“ The worms increase in size with astonishing rapidity, and no less remarkable is their growing voracity. Certain races moult or cast their skin three times during their larval existence, but for the most part the silkworm moults four times—about the sixth, tenth, fifteenth and twenty-third days after hatching. ”

“ SILK.—Four kinds of silkworm are collected for the spinning of yarn used in the embroidery on the Haussa gowns. The best of these is that which feeds upon the Tamarind tree, “Tsamia,” and is termed “Tsamian tsamia.” The silk cocoons are collected in Bauchi Province and are boiled in water with wood ashes, and subsequently washed. The silk becomes nearly white, and is carded and spun into yarn in the same manner as cotton. The species of insect which produces this silk has not yet been identified, but is almost certainly referable to the genus Anaphe (cf. p. 117) . ”

“ Soon the silkworm plague invaded most of the silk-growing countries of Europe. In 1864, only the races of silkworms in China and Japan were surely not infected. Great suffering had been entailed on many departments of France by the failure of the silk industry. The most careful investigation failed to reveal any method of combating the disease. Acute observers had been at work and some very suggestive observations on the affected worms had been made, but the solution of the problem of the prevention of the disease seemed as far off as ever. ”

“ The white-fruited mulberry (M. alba) , a native of China, is the best, and is greatly preferred by the insect."
[1] The silkworm when first hatched is about a quarter of an inch long. After eight days' feeding, it prepares to change its skin. It throws out filaments of silk, attaching its skin to adjacent objects, becomes sluggish, raises the forepart of its body, and finally the whole outer case is cast off, including the feet and jaws. ”

“ This is much cultivated in China, and it is said that garments made of its silk descend from father to son. It is several times larger than the silkworm, and survives even the severe winters of Canada. It would be much easier to raise than the delicate bombyx, or common silkworm. ”

“ This means that worms are reared in the homes of the people, rather than in large establishments. During the silkworm season everything else must give way; the house is filled with trays of ravenous worms; rest, recreation, and sleep, for old and young alike, are neglected in order that the precious worms may get their fill. ”

“ It is the most important of all insects to man, as from it alone all the silk of commerce is obtained. Its cocoon is of a beautiful yellow colour, varying in shade from orange to pale straw-colour; the silk of one cocoon weighs somewhere about three grains; it would therefore, at this calculation, take 1920 worms to spin one pound. The annual import of silk into this country alone is about 7,000,000 pounds, it must therefore take 13,440,000,000 Silkworms to supply us with silk yearly! The Silkworm feeds almost exclusively on the leaves of the mulberry. ”

“ Throughout that region in which Baron Shibusawa spent his boyhood the silkworm is an object of the keenest interest to the people, for everything hinges upon its preservation in a good state of health, and at certain stages of the worm’s existence it is regarded, even at the inns where travellers have to put up for the night when on the road, as a creature whose interests it is necessary to study far more carefully than those of a guest. ”

“ On this account it appears to be impossible for us ever to attain to any kind of sympathetic relations with these creatures.
Even more important than the bees are those insects which, in their immature state, yield us silk. The so-called silkworms, like the bees, originated in Asia, and have long been in the care of man. Beginning their experiments in spinning with the wool of animals and the various accessible vegetable fibres, men have ever been seeking materials which could serve them in the weaver's art. ”

“ The insects appeared quickly to revert to natural conditions; the moths brought out in open air were strongly marked, lively and active, and eggs left on the trees stood the severity of the winter well, and hatched out successfully in the following season. Roland's experience demonstrated that not cold but heat is the agent which saps the constitution of the silkworm and makes it a ready prey to disease. ”

“ If we lose our crop of cocoons because of slighting the little details it [30] will be our own fault, and we shall deserve failure; if, on the other hand, we do the best we know, we shall have no regrets. We must take every precaution to keep the silk-house clean and well-ventilated, for silkworms demand spotless surroundings as well as plenty of fresh air. Then we must not allow withered leaves or other refuse to collect on the shelves where the worms are feeding, for any waste matter ferments and causes disease."
"Aren't silkworms very likely to get sick anyway, Mother?" queried Pierre. ”

“ Eleven different species of silkworm have been enumerated as natives of India, which has thus the internal means of providing the whole of Europe with a material which would rival cotton and woollen cloth, and would often be preferred to both, could it be obtained at a low price. ”

“ But a silkworm does all its growing in a very short space of time, and in proportion to its size grows faster than almost any other living thing. Remember, its whole life is over in a few short weeks. ”

“ Silkworms are liable to several diseases, and in Europe great care is exercised to secure the utmost cleanliness at every stage of rearing. The most dreaded scourge is that known as calcino, which does not manifest itself until the second period of the silkworm's existence. ”