SILICAND The name silk is derived by the not unusual substitution of I for r, from Let. sericum (Gr. serikon), so called as coming from the country of the Seres or Chinese. The Sms-wousr is the caterpillar of the Stix-woust Mom, of which there arc numerous species belonging to the genus born5ge and other genera of the family bombycitice, lepidopterous insects of the section popularly known by the name moth (q.v.). The born5yeida have a very short and rudimentary proboscis, living for a very short time in their perfect state, and taking little or no food; the body is thick and hairy the wings are large and broad, either extended horizontally when at rest, or inclined like the sides of a roof ; the antennm are pectinated. The caterpillars feed on the leaves and other tender parts of trees or other plants; the chrysalids are inclosed in a cocoon of silk, which gives to some of the species a great economical importance. The most important is the Comsrox SILK-WORNI (bom5yx ment), a native of the northern provinces of China. Tlie perfect insect is about an inch in length, the female rather larger than the male; the wings meeting like the sides of a roof; the color whitish, with a broad pile brown bar across the upper wings. The females generally die very soon after they have laid their eggs, and the males do not survive much longer. The eggs are numerous, about the size of a pin's head, not attached together, but fastened to the surface on which they are laid by a !sunily substance, which, when dry, becomes silky. They are laid in the end of summer, anti are hatched in the beginning of next summer. The caterpillar is at first very small, Out more than a quarter of an inch in length, but rapidly increases in size, till. when full grown, it is nearly 3 in. long. It is of a yellowish gray color.
upper The head is large. On the part of the last joint i t of the body is a horn-like process.
The skin is changed four or five times during the growth of the caterpillar. Before each change of skit], it becomes lethargic, and ceases to eat, whereas at other times it is very voracious. When the skin is ready to lie cast off, it bursts at the forepart., and the caterpillar then, by continually writhing its body, without moving from the spot, thrusts it backward; but silk-worms frequently- die during the change of skin. A very , rapid increase of size takes place while the new skin is still soft., The natural food of the silk-worm is the leaves of the white mulberry, but it will also feed on the leaves of some other plants, as the black mulberry and the lettuce. When so fed, however, it produces silk of inferior quality. The silk-producing organs are two large glands (sericteria) containing a viscid substance, which extend along a great part of the body, and terminate in two spinnerets in the mouth. These glands become very large when
the change to the chrysalis or pupa state is about to take place. When about to spin its cocoon, the silk-worm ceases to eat, and first produces the loose rough fiber which forms the outer part of the cocoon, and then the more closely disposed and valuable fiber of its interior. In this process, the position of the hinder part of the body is little changed, but the head is moved from one point to another; and the cocoon when finished is much shorter than the body, which, however, being bent, is completely inclosed in it. The cocoon is about the size of a pigeon's egg. Each fiber of silk, when examined by a m;croscope, is seen to be double, being equally derived from the two -silk-producing organs of the caterpillar. A single fiber often exceeds 1100 ft. in length. The time of the silk-worm's life in the caterpillar state is generally about eight weeks. About five days are occupied in the spinning of the cocoon; after which about two or three weeks elapse before the cocoon bursts and the perfect insect conies foith. The natural burst-. ing of the cocoon is, however, injurious to the silk, and the silk-worm nearer prevents it by throwing all the cocoons into boiling water, except those which he intends to keep in order to the maintenance and increase of his stock. These he selects with care, so that he may have about an equal number of male and female insects, the females being known, even in the chrysalis state, by their larger size. The cocoons intended for the production of moths are placed on a cloth in a somewhat darkened room, of which the temperature is near, but does not exceed, 72° Fahr.; and the moths', when produced, show no inclination to fly away, but remain on the cloth, lay their eggs, and the there. It is an interesting peculiarity of this valuable species of moth, that neither in the caterpillar nor in the winged state does it show that restless disposition which belongs to many others, the caterpillars remaining contentedly in the trays or boxes in which they are placed, feeding on the leaves with which they are there supplied, and at last only seek ing a proper place to assume the chrysalis form on small bundles of t.Wigs which are placed for that purpose above the trays; the perfect, moths, in like manner, abiding almost in one spot, and scarcely caring to use their wings. Owing to this peculiarity it is capable of being reared and managed in a way which would otherwise be impossible.