Manual of Instructions for Raising Mulberry Trees and Silk Worms.
By Authority : George Didsbury, Government Printer, Wellington Wellington: Lambton Quay.1886.
Cultivation of Mulberry Trees.
This manual is not intended to be a scientific treatise on mulberry trees. It has been compiled for the purpose of giving a few practical hints as to the best methods of planting and propagating those varieties which have been found to be most adapted for silkworm food. It is as yet premature to state which is the very best variety of mulberry for New Zealand. General rules and such information as would apply under all circumstances and in all places would be extremely difficult to formulate, and too vague for practical use at any given point. The following rule may, however, with safety be laid down : All mulberry trees the leaves of which are soft, glossy, and smooth on both sides (not prickly or woolly) may be used. With a first-class quality of silkworm eggs and an equal amount of care bestowed on the worms the difference between one variety of tree and another will not amount to much as regards the quantity or quality of the cocoons.
I have submitted this manual for revision and correction to an expert who has had over twenty years" practical experience in New Zealand of planting and propagating trees. Therefore I venture to hope that the instructions given herein will be found useful and in most instances correct.
The best known varieties of the mulberry tree (Morus) are: Morus rubra, red mulberry; Morus nigra, black mulberry; Morus multicaulis, Philippine mulberry; Morus alba, white mulberry.page 4
The red mulberry, so called on account of its fruit, which is of dark red colour, of pleasant, slightly acid taste, is totally unfit for silkworm food. As a rule the worms will not touch its leaves.
The black mulberry is planted for the sake of its fruit, which is of black colour, and has a pleasant taste. The leaves of this variety should only he given in case the food from the white mulberry falls short. The worms have great difficulty in eating the leaves, on account of their being prickly. The worms therefore cannot absorb a sufficient quantity of food, they starve, dwindle, and die, or produce a very poor quality of silk. It is not advisable to use the black mulberry at all for silkworm food.
The multicaulis is chiefly used in Asia and Japan, and—although perhaps not so suited as other varieties, being less rich in nutritive elements—it will do very well for silkworm food. It is a shrub, very prolific, and can be easily and quickly propagated by cuttings and layers.
The white mulberry is the traditional food plant of the silkworm. There are a great many varieties : the best known are Morus Moretti and Morus alba rosea (rose-leaved, or Cevennes). The leaves feel soft, smooth, and glossy. The fruit is of whitish colour and unpleasant taste. The wood is yellowish white, and becomes very hard when the tree gets older. The white mulberry often attains very old age, and will grow over 50ft. high. It is easily propagated from the seed, layers, or cuttings, and this last method is perhaps the quickest and most economical of planting to secure a stock. I am informed, however, by nurserymen that it requires a great deal of time and trouble to propagate the alba rosea from cuttings.
Mulberry trees will grow nearly anywhere except in damp, wet soil. Deep, light, rich or sandy soil from which there is natural drainage is the best. The climate does not seem to affect them much. They are found at Christiania, Norway, with a mean temperature per annum of 41° Fahr., as well as at Canton with a mean temperature of 74° Fahr. In very rich soil the trees will thrive remarkably well, but the leaves contain a minor quantity of nutritive elements. Exposure to page 5 the sun and air benefits them. It has been shown that the leaves of mulberry trees grown in the shade contain as much as 25 per cent. more water than those exposed to the sun. Leaves of middle-aged and old trees contain more nourishment than those of young ones under ten years old. Unless the trees are pruned the leaves get smaller every year, and the trees often die. A fact not generally known is, that the roots of mulberry trees grow nearly straight down instead of spreading horizontally. Thus farmers are enabled to grow cereals and root crops in the same field where mulberrry trees stand. This, however, only applies to standard trees at least 10ft. to 12ft. high.
Extended experiments have lately been made in the United States about the value of the Osage orange, and they appear to have been entirely successful. The raiser says, "Very generally used as a hedge-plant in those sections of the country which are particularly adapted to silk culture, its leaves may at once be obtained without any special investment of capital. Indeed, as the hedges need trimming, the cutting-off the new year's growth is a saving rather than an expenditure. Those who use this plant must, however, bear in mind that the shoots from a hedgerow become very vigorous and succulent by the time the worms are in the last age. These more milky terminal leaves should be thrown aside and not used, as they are apt to induce flaccidity and other diseases. In avoiding these more tender leaves and using only the older and firmer ones consists the whole secret of the successful rearing of silkworms on this plant, and if care be taken in this respect there will be no appreciable difference in the silk crop from Osage orange as compared with that from mulberry. The thorns of the Osage make it somewhat difficult to pick its leaves, and I should not advise its cultivation merely as silkworm food. Every year's experience with the Osage confirms all that I have said of its value as silkworm food. Silk which I have had reeled from a race of worms fed on it now for eleven consecutive years is of the very best quality.
Raising Mulberry Trees.
From Seed.—Plants raised from seed turn out more vigorous than from cuttings or layers.page 6
Where fruit-bearing trees are available collect the berries crush, dry, and put through a fine sieve. Keep the seed in a safe place, as rats and mice are very fond of it. If fruit-bearing trees are not available, apply to a nurseryman, but always ask for Morus alba (white). Seed from old trees is preferable.
Sow in the early spring in deep, rich, light, soil, if possible in a sheltered place. If in an open place, stick branches of ti-tree or other scrub in the ground, to protect the seedlings from the fierce rays of the sun in the late spring. Towards autumn the branches may be removed. Sow in rows Gin. apart, about ½in. deep. Cover, rake, and beat gently with the hack of a spade. If the seed is soaked in water for two or three days before sowing the seedlings should make their appearance in about three weeks; at the end of the first year they should be about 12in. high.
Some time during the first winter they are lifted from the seed-bed and planted into nursery rows about 18in. apart, and the young plants about 9in. apart. Before planting, cut them back to about 4in., and when planting cover the roots about the same depth as they occupied in the seed-bed.
If the seedlings are left without cutting back they will produce too many branches, making it more difficult to train them into proper shape later on, when they are set out into permanent position. If only two or three eyes are allowed to grow, these will in time become strong, sound branches, giving a better opportunity, the following season, of raising a well-built tree. This method is somewhat slow, but raisers will find it to their advantage to raise high-stemmed trees, because the older the tree gets the more leaves it will yield, until as much as lewt may be got from one tree. This does not apply to Multicaulis, it being a shrub. During the growing season keep free from weeds.
At the end of the second season the young trees should be about 3ft. or 4ft. high. At Home the seedlings leave the nursery after the third year; in the northern part of New Zealand they may be set out after two years—that is, in the spring of the third year. Never transplant without pruning off all jagged ends of the roots.
When planting out in permanent positions plant them the page 7 same depth as they were in the nursery bed. If intended to raise dwarfs, 10ft. apart, if standards, 15ft.
Dwarfed trees are preferred by many people because it is easier to gather the leaves, but of course they do not yield the same quantity as full-grown high-stemmed trees.
Trees should be pruned every year; the best time is after the silkworm season is over, or in spring, when the leaves make their appearance and the silkworm eggs are hatched, so as to be able to use the leaves on the cut-off twigs for food.
In pruning train the head in the shape of a cup, causing the branches to come out horizontally from the stem, so as to give space in the centre for free admission of light and air. It will also facilitate the gathering of leaves.
Grafting.—Some people have found it advantageous to graft the white on to the black mulberry, the latter being hardier.
Layering.—Mulberry trees can very easily be propagated by this method, which requires no further explanation. Hedges may be formed in this way.
Cuttings.—Plant cuttings in rows 4in. apart, in well-dug ground. They should be about 9in. long, with two or three eyes at the top of each cutting. The rest of the eyes are rubbed off. Bury them about Gin. in the ground. The second season treat them like seedlings.
The height of the tree and its shape are easily regulated by pruning, and upon this process depends not only the vigorous growth of the tree, but also the ease with which the leaves may be gathered when wanted. All dead twigs should be removed, and the limbs kept as smooth as possible.
The best times for planting are the months of July and August.
Enemies and Diseases.
Cattle, sheep, goats, hares, and rabbits are very fond of the leaves and twigs. Slugs and snails eat the buds as they burst, and if not looked after will destroy numbers of plants, especially seedlings. Sprinkle lime over the seed-bed or cuttings after dark, when the grubs are feeding. This must be done frequently, as the lime soon loses its killing powder. Attention need page 8 only be given to the above during the earlier stages of the plant's growth.
Borer.—This insect is very common. It seems to he particularly fond of mulberry trees. Branches attacked by the borer should be cut below the extremity of the burrow, and destroyed (burnt). Probing the galleries with wire has been found effectual. Some people inject soapsuds, mixed with a little carbolic acid. If the roots penetrate into cold, wet soil
Foot-rot may be caused.
Blight is less frequent. Where it makes its appearance castor-oil, mixed with a little soot, should be applied with a brush.
The chief points to keep a mulberry tree healthy are—Plant in dry, light, well-drained soil; do not allow any useless growth; do not allow the branches to interlace; admit plenty of light and air, so as to give as little cover to insects as possible; remove primings, moss, and lichen from trunks and branches; keep ground clear from grass and weeds.
Instructions for Silkworm-Raising.
The purport of this portion of the manual is to give, in a simple and condensed form, the necessary instructions for raising silkworms. Professor Riley, who is perhaps the greatest authority in America on silk culture, in a special report to the United States Department of Agriculture, makes some remarks which apply equally well to New Zealand. He says, "To avoid the disappointment that is sure to follow exaggerated and visionary notions on the subject, it may be well here to emphasize the facts—that the profits of silk culture are always limited; that extensive operations by organized bodies must prove unprofitable where capital finds so many more lucrative fields for employment; that extensive silk-raising is fraught with dangers that do not beset less ambitious operations; that silk culture, in short, is to be recommended only as a light and pleasant employment for those members of the farm or the household who either cannot do or are not engaged in otherwise remunerative work. The greater value of labour here as compared with labour in the older silk-growing countries has been in the past a most serious obstacle; but conditions exist to-day that render this obstacle by no means insuperable. In the first place, comparative prices are often misleading. The girl who makes only 1s. a day in France or Italy does as well as she who earns three or four times as much here, because of the relatively lower prices of all commodities there. Again, the conditions of life are such in those countries that every woman among the agricultural classes finds a profitable avenue for her labour in field and factory, so that the time given to silk-raising must be deducted from other profitable work in which she may be employed. With us, on the contrary, there are thousands and thousands of persons—women, children, page 10 old people—who, from our very condition of life, are unable or unwilling to labour in the field or factory, and have, in short, no opportunities of converting labour into capital. The time that such people might give to silk culture would therefore be pure gain; and in this sense the cheap-labour argument looses all its force. The most serious obstacle to be overcome is the want of a ready market for the cocoons. A permanent market once established the other obstacles will slowly but surely vanish as snow before the coming spring. Silk culture must depend for its growth on the production of cocoons. It will not be safe for individuals to rely on reeling their own silk. The art of reeling in modern filatures, and with steam appliances, has been brought to such perfection that none but skilled reelers can hope to produce a first-class article. Besides, it is difficult to dispose of small parcels of raw silk at satisfactory prices."
Large establishments for rearing silkworms, where as many as 60oz. (2,000,000 worms) were raised in one season, are fast disappearing. The crops now consist of so many thousand small lots raised by a corresponding number of families. To produce a few pounds of cocoons each year does not materially interfere with the household or other duties people may he engaged in, and it is by each household raising a few pounds of cocoons that silk culture must be carried on in this as it is done in other countries.
Professor Riley considers that the following are the most important requisites to successful silkworm culture : (1) Cleanliness; (2) fresh air and as uniform a temperature as possible; (3) plenty of room, so that the worms may not too closely crowd each other; (4) no intermission in the supply of fresh food, except during the moulting periods; (5) uniformity of age in the worms of the same tray, so as to insure their moulting simultaneously; to which might be added, a sufficient number of trees for the supply of leaves.
Definite rules are of little avail, as much depends on circumstances and conditions. Beginners will do well to hatch only a small quantity of eggs. If not successful the first year not much is lost. With a year's experience there will be a better chance of success and of profit the second year.
There is an inclination, among people who are unable to pro- page 11 duce first-class cocoons at the start, to blame the industry if they do not receive what they consider an adequate compensation for the time which they have expended upon the work; and yet these same individuals would not expect to be successful in any other enterprise until they had made themselves thoroughly acquainted by practical experience with the special work involved.
The introduction of silk culture will in time result in a very important yearly revenue, and increase in the public wealth. This, however, may be a less advantage than the fact that, by supplying a new home industry, it would do much towards conserving home tics and interests, and help to strengthen and perpetuate home-living among the people.
The silkworm exists in four states—egg—larva—chrysalis—moth.
Eggs, or graine, or seed.—The eggs are of gray, slate, violet, or dark green colour, according to breed. If unimpregnated (that is, not capable of hatching) or dead they are white or yellowish white. The old Italian and French varieties produce yellow silk, and the Japanese variety, white or greenish silk: these are considered the best. These eggs are covered with a gummy substance, by which they stick on the objects they are laid upon. They are best kept in boxes of perforated tin in a cool, dry, well-ventilated place. Examine them occasionally. If mouldy, brush off and remove at once to a drier place. The temperature should not be above 50° Fahr., but may sink to freezing point without injury. Beware of rats, mice, ants, &c. The eggs remain in a dormant state from seven to nine months. Hatching may be accelerated by heat or retarded by cold. When the trees are well out in leaf the eggs are hatched. By this time they have assumed a slightly lighter colour.
Hatching.—Put the eggs in a room where the temperature is 75° Fahr. Increase the temperature gradually to 80° or, if necessary, to 90°, but not more. In five to eight days, at the latest, the little worms will appear. Do not expose the eggs to the rays of the sun. If they have been wintered adhering to the cloth or paper upon which they were laid they may be hatched on the same; if in loose condition, they must be spread evenly over sheets of paper or cloth. Large quantities are page 12 hatched in an incubator. An incubator may be constructed from pasteboard, in the shape of a box, square or round but tight-fitting, about 2ft. high. Fix a tray near the top made of wire-netting, upon which the cloth or paper with the eggs is laid. Put a small spirit-lamp inside, with a small vessel of water over it, about half way up. But the water must not boil: it is simply put there to create a humid heat, which facilitates the hatching. A thermometer is, as a rule, also fixed inside.
The Larva or Silkworm proper.—The colour of the newly-hatched worms is black or dark grey. They become lighter as they grow older, until the spinning time, when they are of cream white colour. The worm undergoes four moults or sicknesses (casting of the skin). The first moult takes place between the fourth and sixth day after hatching, the second about the tenth, the third about the sixteenth, the fourth about the twenty-fourth day. The periods of sickness last from thirty-six to sixty hours. Thirty-five days after hatching is the normal time for the worms to begin to spin. Just before and after each moult the worms eat voraciously, and between the fourth moult and the time for spinning the quantity of food consumed is surprising.
Any Room or Shed will do to raise silkworms if it is dry and can be thoroughly ventilated. Small quantities can be raised on trays upon tables. The kitchen is a good place. The worms will never leave the trays if properly attended to, that is, if they have a sufficient supply of food, and the temperature is kept even. Large broods are raised on shelves arranged along the walls, or fixed on racks from floor to ceiling, or the trays may be suspended by wires from the ceiling.
Width of Trays 4ft. or 5ft., depth 3in. or 4in., length according to room. Put them 18in. to 2ft. apart. The wood they are made of must be well seasoned, non-resinous, in fact have no smell. The bottom is of wire-netting, cane, or simple slats. The trays must be covered with strong paper. A room 18ft. by 20ft., with two shelves all round, safely accommodates forty thousand worms; that is the issue of one ounce of eggs.
Raising Silkworms.—When the eggs begin to hatch mosquito netting or perforated paper is laid over them. Upon this spread freshly-plucked leaves. The little worms will rise through the meshes or holes and make for the food, when they can be easily page 13 removed to the trays where they are going to be raised. For small broods it is sufficient to put some fresh leaves on the worms. They will crawl on to them, and are then moved. As the worms grow older the size of the meshes of the net or the holes of the paper has to be increased. They have to be moved on clean paper for the purpose of cleaning the trays (removing the litter). The smell of decayed and fermenting leaves is injurious to them—in fact, they dislike all bad smells. Coarse twine netting may be used for the same purpose. Each day's hatching should be kept separate, so that the worms go through different moultings with uniformity. Any eggs not hatched after the fourth day (after hatching began), are not worth keeping. They contain inferior worms, and are best thrown away.
Feeding.—It is recommended by some that the leaves be hashed, that is, minced with a knife like you would prepare lettuce for salad. This is advisable if they are old, but it is not necessary if the hatching takes place when the leaves are still young and tender. With small broods it may be done during the first two ages, but it is not necessary after the second moult. Besides giving a lot of trouble, hashed leaves dry quicker, and the food has to be renewed oftener.
As to the number of times of feeding, practical experience alone will teach how to proceed. The food should be renewed whenever the preceding supply has been devoured or become dry. During the last two stages as a rule six meals are given, with one substantial one late at night, and another the first thing in the morning.
I would strongly recommend to use only mulberry leaves, and rather decrease the number of worms than use other food.
Never feed with wet, soiled, withered, or partly-decayed leaves; they breed disease.
Spread leaves evenly, so that all may feed alike.
If wet, shake them in a cloth. As rain is very frequent in most parts of New Zealand it would be advisable to pick a day's supply of leaves beforehand, and keep them in a cool place.
Leaves are, as a rule, stripped from the trees. Some people cut branches off, and so prune the trees at the same time.
The temperature should always be kept between 70° and 80° Fahr. Keep it as even as possible during the moulting periods. page 14 With a high and even temperature, say, 75°, the worms will enjoy excellent health and appetite, and consequently make more silk. During the daytime, when the temperature outside is about 70° or more, the windows may be kept open; but the worms must not be exposed to the rays of the sun.
Moulting.—The worms leave off eating, and feeding should cease. Some will moult much quicker than others; but they may be left half a day without food, so as to wait until the majority have cast their skins. There will nearly always he a few which remain sick after the others have started feeding again. If they appear weak and languid destroy them; they would only contaminate the others. If they are only smaller in size, but otherwise healthy and vigorous, keep them separate, or the batch will grow more and more irregular. They may be moved with a quill pen; but it is better to touch silk worms as little as possible.
The importance of keeping each batch together and so causing the worms to moult at the same time cannot be too much insisted upon. When the moult is completed, feed copiously. They grow rapidly after each moult. When too crowded divide the batch.
The fourth moult is the most critical. Afterwards they will eat for about ten days longer, and the litter should be often removed during this period. They will eat ravenously about the thirtieth day, but leave off gradually, decrease somewhat in size, become nearly transparent, and sway their heads to and fro in search of something. Now they are ready to spin.
Spinning.—Arches of broom, corn, or brush must be prepared. They should interlock, and be about 12in. to 18in. high. Some people use a cocooning ladder made of lattice-work, others put wood shavings on the trays, or paper tubes. The brush must be dry, and have no smell.
The temperature should be kept about 75° to 80°. The worms will mount immediately into the branches and begin to spin. A few may not mount. Put some brush for these on the trays. Allow plenty of room, so as to prevent two worms joining and forming only one cocoon. These double cocoons have a much lower market value. Before the worms spin they emit a dirty fluid, which stains and injures cocoons on which it might page 15 drop. This will occur seldom if they have plenty of room and start spinning about the same time. In about eight or ten days the cocoon will he finished, and the worm inside has reached the third or chrysalis state. A rattling sound is heard if the cocoon is shaken; but, to make quite sure, the best plan is to cut a few cocoons with a knife.
Cocoon.—The cocoon consists of an outer lining of loose, woolly silk called " floss silk," and an inner part, "the pod," which should he strong and compact, composed of a firm continuous thread. This is the part used for reeling, and upon its consistency (quantity of silk) and the fineness and gloss of its texture depends the commercial value of the cocoon.
The Chrysalis requires no special description. It makes excellent manure. The chrysalis state lasts from twelve to twenty days, when the skin bursts, and the moth emerges.
After about eight days from the time spinning commenced the cocoons may be gathered, and are now ready for the market. Where reeling establishments are at hand the cocoons may be delivered at once, after the floss silk has been taken off. In New Zealand (there being no filatures as yet) it will be better to choke the chrysalis and dry the cocoons. Their weight will decrease about 60 per cent., but their price will increase in exact proportion—that is, 31b. become 11b.; but it is the chrysalis which dries and causes the decrease of weight, and not the silk. Cocoons with the grubs dried are called "dry cocoons," the others "fresh cocoons."
Some people having hand-reels might choose to reel their cocoons. To these I would recommend not to reel only one cocoon at a time, as such silk is not marketable. Raw silk consists of the threads of from three to six cocoons combined in one, according to the different sizes required in the market. Italian and French reelers have acquired perfection, and we cannot compete, for various reasons. But persons reeling for amusement might make excellent fishing-lines.
Choking the Chrysalis.—All cocoons which are not intended for reproduction (about which later on) must undergo the process of having the grubs killed, otherwise all the moths would in course of time work their way out of the cocoons. Such cocoons—pierced cocoons—cannot be reeled, but have to be carded like cotton or wool. They are of little value.page 16
Cocoons may be choked by dry heat or by steaming. Put them in an oven with a temperature of about 150° Fahr. Two hours will suffice. By this method the silk is often burned, if not carefully looked after. Where facilities are at hand steaming is by far the better and surer method. Put the cocoons in a tightly-fitting box, make a hole, and turn the steam in. Half an hour will do it. For small quantities it is recommended to put them in shallow baskets or boxes and expose them to the rays of the sun for two or three days; cover with glass panes, and leave a small opening for moisture to evaporate. Cessation of a certain humming noise is an indication of the chrysalis being dead; but the surest way of ascertaining the fact is again to cut a few cocoons and examine the chrysalis by pricking it with a pin.
This operation completed, the cocoons are put again on shelves, not more than 3in. deep, and left to dry. Plenty of air should be admitted, and the cocoons frequently stirred. After this they may be kept for any length of time, but they are still liable to attacks from rats and mice.
Selecting Cocoons for Reproduction.—Those people who intend to raise silkworm eggs for the next season will have to make provision accordingly. When the cocoons are taken from the bush the largest and firmest should be selected for breeding purposes. Double cocoons must not be used. They are recognizable by their extraordinary size and unusual shape. Soiled cocoons, if large and firm, may be used. Take, say, fifty cocoons, half males, half females (more or less), which will produce about ten thousand eggs. Male cocoons are, as a rule, constricted in the middle; female cocoons are not, but more round, and rather larger. However, it is not always safe to go by this rule. A safer method seems the following, recommended by Riley :Weigh a hundred cocoons, and strike the average : all above the average will be found to be females. Paste these selected cocoons on paper or cloth, and in from twelve to twenty days the moth will have worked itself out of the cocoon.
The Moth.—The fourth and last state of the silkworm. The moth emits a strong fluid, which moistens the end of the cocoon, and dissolves the gummy lining. Then the moth emerges. The moth is of cream colour. Neither sex flies, but the males flutter page 17 continually with their wings. Females have larger bodies than males. They issue mostly early in the morning, and couple soon afterwards.
Egg-laying, or Reproduction.—Keep the room dark. If necessary, place sexes together. Destroy all that are deformed. Should more males issue the first day than females, keep them in a box until the next day, when the reverse may be the case. Strong males may be used twice. They should remain together six to eight hours. If not uncoupled after twelve hours, separate them. Handle them gently, by getting hold of their wings and bringing their heads together. The males may be thrown away when all the females have been impregnated. Put the females on blotting-paper first, where they will discharge a yellowish fluid. From there put them on woollen or linen stuff or paper (in a slightly-slanting position), where the moth will lay her eggs (300 to 400). They are laid very regularly, as the moth very seldom leaves the spot. After two days the moth is removed, as all eggs worth having will be laid by that time.
Let the eggs dry, and after a week they may be stored away in a cool, dry place until the following season. They are best kept on the cloths they were laid upon. When deposited the eggs are yellow, and this colour they retain if unimpregnated; otherwise they assume a darker colour, and become indented. The female moths may be thrown away also.
In Italy and France the female moths are kept for the purpose of microscopical examination, so as to ascertain whether the eggs are healthy or not. Silk culture is in its infancy yet in New Zealand, and I am not aware of any diseases having shown themselves in the few cases where people have raised silkworm eggs. I refrain, therefore, from giving a description of those terrible diseases which made their first appearance in Europe about twenty years ago, and nearly ruined the industry, but which, thanks, chiefly, to the researches of Pasteur, were successfully combated. I sincerely trust I shall never have occasion to refer to them as existing in New Zealand.page 18
|First day to fifth||75°||to 80° Fahr.||9lb. leaves.||12 sq. ft.|
|Seventh day to tenth||72° to 75 Fahr.||24lb. leaves.||24 sq. ft.|
|Eleventh day to sixteenth||72° to 75° Fahr.||80lb. leaves.||60 sq. ft.|
|Seventeenth day to twenty-third||72° to 75° Fahr.||260lb. leaves.||140 sq. ft.|
|Twenty-fourth day to twenty-eighth||75°||Fahr.||1,000lb||350 sq. ft.|
|Twenty-ninth day to thirty-fifth||75°||Fahr.||1,000lb||600 sq. ft.|
- After first moult;
- Between second and third moult, once or twice;
- Between third and fourth moult, twice;
- After fourth moult, three or four times.
|First age||81b.||10 square feet.|
|Second age||24lb.||30 square feet.|
|Third age||65lb.||50-75 square feet.|
|Fourth age||200lb.||100—160 square feet.|
|Fifth age||1,200lb.||320 square feet.|
|Fifth age||1,200lb.||430—640 square feet.|
These figures are based on practical experience in Italy and the United States. Raisers will, however, do well to be guided by their own common-sense and observations as to renewal of food and increase of accommodation.
Average number of eggs per ounce, 37,000 to 40,000.
Average number of fresh cocoons per lb., 300 to 400.
Maximum amount of fresh cocoons from loz. of eggs, 1501b.
Average amount of fresh cocoons from loz. of eggs, 801b. to 1001b.
Two adults can easily take charge of 2oz., or 80,000 worms.
31b. to 3½b. of fresh cocoons equal to 1lb. dry cocoons.
One moth lays three to four hundred eggs.
3½b. to 4lb. of dry cocoons make 1lb. raw silk.page 19
101b. to 121b. of fresh cocoons make 1lb. raw silk.
Length of thread from one cocoon, 800 to 1,500 yards, according to breed.
Temperature in Auckland during October, November, and December; and Rainfall.
By Authority: George Didsbury, Government Printer, Wellington.—1886.