A Chinese banker in Chekiang province, with whom we talked, stated that the young worms which would hatch from the eggs spread on a sheet of paper twelve by eighteen inches would consume, in coming to maturity, 2660 pounds of mulberry leaves and would spin 21.6 pounds of silk. This is at the rate of 123 pounds of leaves to one pound of silk. The Japanese crop for 1907, 26,072,000 pounds, produced on 957,560 acres, is a mean yield of 27.23 pounds of raw silk per acre of mulberries, and this would require a mean yield of 4465 pounds of green mulberry leaves per acre, at the rate of 164 pounds per pound of silk.
Ordinary silk in these countries is produced largely from three varieties of mulberries, and from them there may be three pickings of leaves for the rearing of a spring, summer and autumn crop of silk. We learned at the Nagoya Experiment Station, Japan, that there good spring yields of mulberry leaves are at the rate of 400 kan, the second crop, 150 kan, and the third crop, 250 kan per tan, making a total yield of over thirteen tons of green leaves per acre. This, however, seems to be materially higher than the average for the Empire.
In Fig. 188 is a near view of a mulberry orchard in Chekiang province, which has been very heavily fertilized with canal mud, and which was at the stage for cutting the leaves to feed the first crop of silkworms. A bundle of cut limbs is in the crotch of the front tree in the view. Those who raise mulberry leaves are not usually the feeders of the silkworms and the leaves from this orchard were being sold at one dollar, Mexican, per picul, or 32.25 cents per one hundred pounds. The same price was being paid a week later in the vicinity of Nanking, Kiangsu province.
The mulberry trees, as they appear before coming into leaf in the early spring, may be seen in Fig. 189. The long limbs are the shoots of the last year's growth, from which at least one crop of leaves had been picked, and in healthy orchards they may have a length of two to three feet. An orchard from a portion of which the limbs had just been cut, presented the appearance seen in Fig. 190. These trees were twelve to fifteen years old and the enlargements on the ends of the limbs resulted from the frequent pruning, year after year, at nearly the same place. The ground under these trees was thickly covered with a growth of pink clover just coming into bloom, which would be spaded into the soil, providing nitrogen and organic matter, whose decay would liberate potash, phosphorus and other mineral plant food elements for the crop.
In Fig. 191 three rows of mulberry trees, planted four feet apart, stand on a narrow embankment raised four feet, partly through adjusting the surrounding fields for rice, and partly by additions of canal mud used as a fertilizer. On either side of the mulberries is a crop of windsor beans, and on the left a crop of rape, both of which would be harvested in early June, the ground where they stand flooded, plowed and transplanted to rice. This and the other mulberry views were taken in the extensively canalized portion of China represented in Fig. 52. The farmer owning this orchard had just finished cutting two large bundles of limbs for the sale of the leaves in the village. He stated that his first crop ordinarily yields from three to as many as twenty piculs per mow, but that the second crop seldom exceeded two to three piculs. The first and second crop of leaves, if yielding together twenty-three piculs per mow, would amount to 9.2 tons per acre, worth, at the price named, $59.34. Mulberry leaves must be delivered fresh as soon as gathered and must be fed the same day, the limbs, when, stripped of their leaves, at the place where these are sold, are tied into bundles and reserved for use as fuel.
In the south of China the mulberry is grown from low cuttings rooted by layering. We have before spoken of our five hours ride in the Canton delta region, on the steamer Nanning, through extensive fields of low mulberry then in full leaf, which were first mistaken for cotton nearing the blossom stage. This form of mulberry is seen in Fig. 43, and the same method of pruning is practiced in southern Japan. In middle Japan high pruning, as in Chekiang and Kiangsu provinces, is followed, but in northern Japan the leaves are picked directly, as is the case with the last crop of leaves everywhere, pruning not being practiced in the more northern latitudes.
Not all silk produced in these northern countries is from the domesticated Bombyx mori, large amounts being obtained from the spinnings of wild silkworms feeding upon the leaves of species of oak growing on the mountain and hill lands in various parts of China, Korea and Japan. In China the collections in largest amount are reeled from the cocoons of the tussur worm (Antheraea pernyi) gathered in Shantung, Honan, Kweichow and Szechwan provinces. In the hilly parts of Manchuria also this industry is attaining large proportions, the cocoons being sent to Chefoo in the Shantung province, to be woven into pongee silk.
M. Randot has estimated the annual crop of wild silk cocoons in Szechwan at 10,180,000 pounds, although in the opinion of Alexander Hosie much of this may come from Kweichow. Richard places the export of raw wild silk from the whole of China proper, in 1904, at 4,400,000 pounds. This would mean not less than 75,300,000 pounds of wild cocoons and may be less than half the home consumption.
From data collected by Alexander Hosie it appears that in 1899 the export of raw tussur silk from Manchuria, through the port of Newchwang by steamer alone, was 1,862,448 pounds, valued at $1,721,200, and the production is increasing rapidly. The export from the same port the previous year, by steamer, was 1,046,704 pounds. This all comes from the hilly and mountain lands south of Mukden, lying between the Liao plain on the west and the Yalu river on the east, covering some five thousand square miles, which we crossed on the Antung-Mukden railway.
There are two broods of these wild silkworms each season, between early May and early October. Cocoons of the fall brood are kept through the winter and when the moths come forth they are caused to lay their eggs on pieces of cloth and when the worms are hatched they are fed until the first moult upon the succulent new oak leaves gathered from the hills, after which the worms are taken to the low oak growth on the hills where they feed themselves and spin their cocoons under the cover of leaves drawn about them.