The foundations of Japan

by J. W. Robertson Scott

THE BIRTH, BRIDAL AND DEATH OF THE SILK-WORM

(NAGANO)

The mulberry leaf knoweth not that it shall be silk.—Arab proverb

One acre in every dozen in Japan produces mulberry leaves for feeding the silk-worms which two million farming families—more than a third of the farming families of the country—painstakingly rear.

But the mulberry is not the only mark of a sericultural district. Its mark may be seen in the tall chimneys of the factories and in the structure of the farmers' houses. Breeders of silk-worms are often well enough off to have tiled instead of thatched roofs; they have frequently two storeys to their dwellings; and they have almost always a roof ventilator so that the vitiated air from the hibachi-heated silk-worm chambers may be carried off. Yet another sign of sericulture being a part of the agricultural activities of a district is its prosperity. Silk-worms produce the most valuable of all Japanese exports. Japan sends abroad more raw silk than any other country. [^[139]]

It is in the middle of the country that sericulture chiefly nourishes. The smallest output of raw silk is from the most northerly prefecture and from the prefecture in the extreme south-west of the mainland. But human aptitude plays its part as well as climate. The Japanese hand is a wonderful piece of mechanism—look at the hands of the next Japanese you meet—and in sericulture its delicate touch is used to the utmost advantage.

The gains of sericulture are not made without corresponding sacrifices. Silk-worm raising is infinitely laborious. The constant picking of leaves, the bringing of them home and the chopping and supplying of these leaves to the smallest of all live stock and the maintenance of a proper temperature in the rearing-chamber day and night mean unending work. The silk-worms may not be fed less than four or five times in the day; in their early life they are fed seven or eight times. This is the feeding system for spring caterpillars. Summer and autumn breeds must have two or three more meals. The men and women who attend to them, particularly the women, are worn out by the end of the season. "The women have only three hours' rest in the twenty-four hours," I remember someone saying. "They never loose their obi."

When the caterpillars emerge from the tiny, pin-head-like eggs of the silk-worm moth they are minute creatures. Therefore the mulberry leaves are chopped very fine indeed. They are chopped less and less fine as the silk-worms grow, until finally whole leaves and leaves adhering to the shoots are given. Some rearers are skilful enough to supply from the very beginning leaves or leaves still on the shoots. The caterpillars live in bamboo trays or "beds" on racks. In the house of one farmer I found caterpillars about three-quarters of an inch long occupying fifteen trays. When the silk-worms grew larger they would occupy two hundred trays.

The eggs, when not produced on the farm, are bought adhering to cards about a foot square. There are usually marked on these cards twenty-eight circles about 2 ins. in diameter. Each circle is covered with eggs. The eggs come to be arranged in these convenient circles because, as will be explained later on, the moths have been induced to lay within bottomless round tins placed on the circles on the cards. The eggs are sticky when laid and therefore adhere. In a year 35,000,000 cards, containing about a billion eggs, are produced on some 10,000 egg-raising farms.

The eggs—they are called "seed"—are hatched in the spring (end of April—as soon as the first leaves of the mulberry are available—to the middle of May), summer (June and July) and autumn (August and October). It takes from three to seven days—according to temperature—for the "seed" to hatch, and from twenty to thirty-two days—according to temperature—for the silk-worms to reach maturity. Half the hatching is done in spring. In one farmer's house I visited in the spring season I found that he had hatched fifty cards of "seed." From the birth of the caterpillars to the formation of cocoons the casualties must be reckoned at ten per cent. daily. Not more than eighty-five per cent. of the cocoons which are produced are of good quality. The remainder are misshapen or contain dead chrysalises. As there are more than a thousand breeds of silk-worm, all cocoons are not of the same shape and colour. Some are oval; some are shaped like a monkey nut. Most are white but some are yellow and others yellow tinted.