Sericulture

SERICULTURE The art of sericulture concerns itself with the rearing of silk worms under artificial or domesticated conditions, their feeding, the formation of cocoons, the securing of these before they are injured and pierced by the moths, and the maturing of a sufficient number of moths to supply eggs for the cultivation of the follow ing year. The first essential is a stock of mulberry trees adequate to feed the worms in their larval stage. The leaves preferred in Europe are those of the white-fruited mulberry, Morus alba, but there are numerous other species which appear to be equally suitable. The soil in which the mulberry grows, and the age and condition of the trees, are important factors in the success of silkworm cultivation ; and it has been too often proved that the mulberry will grow in situations where, from the nature of the leaf the trees put forth and from other circumstances, silkworms cannot be profitably reared. An elevated position with dry, fri able, well-drained soil produces the best quality of leaves. Throughout the East the species of mulberry cultivated are nu merous, but, as these trees have been grown for special purposes at least for three thousand years, they show the complex varia tions peculiar to most cultivated plants.

Incubation and Rearing of

eggs of the silk worm, called "silk-seed" (Fr. graines), are hatched out at the period when the mulberry buds are breaking into leaf. The hatching is natural where the climate is uniformly hot, but in countries where the silkworm has been introduced, artificial heat has to be applied to the eggs. In many parts this is done by the primitive fashion of imparting to the seed the necessary heat by contact with the human body, but this gives an irregular and unduly protracted hatching. Simple incubators are now in use which make incubation regular, and the eggs all hatch out to gether, which is a great advantage from the point of view of economical feeding later on. The eggs are very minute—about zoo weighing a grain; and a vast number of hatched worms may at first be kept in a small space ; but as the worms grow and require more and more leaves, the caterpillars require quickly increasing and ample space. The seed is distributed in perforated boxes to rearers, as it requires air all through the period of preser vation until the worms are hatched. The boxes are opened and the seed is evenly spread on trays which are placed into the incubator; the lamp of the incubator is lit and the temperature is brought to 65° F. This is gradually increased daily by about 2° until it reaches 77°, at which temperature hatching takes place. The trays are withdrawn from the incubator and per forated paper or open-mesh gauze is spread over the minute worms ; mulberry leaves, now young and very tender, are finely chopped and spread over the paper or gauze ; the little worms wriggle up through the holes and begin feeding. The temperature

of the room in which they are placed should be maintained at 77°. In more progressive countries, a special rearing house (Fr. mag nanerie) is allocated to the rearing of silkworms; it may be used for other purposes during the remainder of the year provided it is swept clean, disinfected and lime-washed ready for the reception of the worms. In more backward places, the dwelling of the peasant rearer is utilized, but the same scrupulous disinfection and cleanliness should be observed, though this is often neglected with unfortunate effects on the worms and the rearer. The place set apart for rearing should be well ventilated, but not necessarily well lit, in deed, it should be capable of shading the worms from the direct rays of the sun, which are detrimental to them.

Though there are many methods of keeping the worms during feeding, the best is probably to erect shelves about three feet wide in the centre of the room so that there is a walking space between them and the walls all round and gangways intersect ing them. These shelves are constructed by means of light scantling from the floor to the ceiling with cross-pieces at inter vals of two feet, the lowest being two feet above the floor. Over the frame-work thus created is laid large-mesh wire netting which, in this way, provides a series of shelves each two feet high. Paper is spread over the wire and the worms are placed on this; the worms increase in size with astonishing rapidity and they are given more and more space in conformity with their growth. No less remarkable is their growing voracity. After three or four days they are sufficiently grown to be able to consume whole young leaves, and from this time onwards their powers of consumption run parallel with the maturity of the mulberry. The feeding lasts about 42 days, but during that time the worm passes through four periods of sleep lasting 24 hours each; some races have only three periods of sleep, but these are rare. During this sleeping period the skin of the worm cracks and when the creature wakes up it is able to shed the old skin and continue with the new one. The importance of the regularity of hatching out now becomes ap parent. The worms hatched out on the same day all sleep at the same time, and during the sleep do not require nourishment. If, however, the hatching out is irregular, sleeping and active hungry worms are mixed up, with the risk either of a waste of mulberry leaf or of malnutrition of the active worms. Worms will not touch faded leaves; the latter must be green but very slightly wilted. The sleeping periods occur on the sixth, twelfth, eighteenth and twenty-sixth day after hatching. After the fourth sleep, the worms start their great and final feed, lasting for ten days during which period they consume about twenty times their own weight of leaves.