508 



HISTORY OF liNSECTS. 



position. It was most probably brought among 

 them from the remotest parts of the East ; 

 since it was, at. the time of which I am speak- 

 ing, scarcely known even in Persia. 



Nothing can be more remote from the truth, 

 than the manner in which their historians 

 describe the animal by which silk is produced. 

 Pausanias informs us, that silk came from the 

 country of the Seres, a people of Asiatic 

 Scythia ; in which place an insect as large as 

 the beetle, but in every other respect resembl- 

 ing a spider, was bred up for that purpose. 

 They take great care, as he assures us, to feed 

 and defend it from the weather ; as well dur- 

 ing the summer's heat as the rigours of winter. 

 This insect, he observes, makes its web with 

 its feet, of which it has eight in number. It 

 is fed for the space of four years upon a kind 

 of paste, prepared for it ; and at the beginning 

 of the fifth, it is supplied with the leaves of 

 the green willow, of which it is particularly 

 fond. It then feeds till it bursts with fat ; 

 after which they take out its bowels, which 

 are spun into the beautiful manufacture so 

 scarce and costly. 



The real history of this animal was unknown 

 among the Romans till the time of Justinian ; 

 and it is supposed, that silk-worms were not 

 brought into Europe till the beginning of the 

 twelfth century ; when Roger, of Sicily, 

 brought workmen in this manufacture from 

 Asia Minor, after his return from his expedi- 

 tion to the Holy Land, and settled them in 

 Sicily and Calabria. From these the other 

 kingdoms of Europe learned this manufacture ; 

 and it is now one of the most lucrative carried 

 on among the southern provinces of Europe. 



The silkworm is now very well known to be 

 a large caterpillar, of a whitish colour, with 

 twelve feet, and producing a butterfly of the 

 moth kind. ' The cone on which it spins, is 



wheels, and 97,746 movements, which worked 73,726 

 yards of organzine thread with every revolution of the 

 water-wheel, whereby the machinery was actuated. So 

 rapid was the growth of the silk trade from this time, 

 that in 1783 the estimated value of silk goods manufactured 

 in England was 3,350,000. 



A great improvement had been effected (ten years 

 before, viz. 1772) in Bengal raw silk. Better machinery 

 being brought into use on the Italian system, and com- 

 petent persons employed as heads of each factory. The 

 shipments about this period, being from 515,000 to 

 560,000 Ibs., have steadily increased to 1,500,000 Ibs. 

 annually. In Italy there is but one regular crop in the 

 year ; while in Bengal there are three at intervals of four 

 months, March, July, and November. 



1 The silkworm, like all other insects of the same class, 

 undergoes a variety of changes during the short period of 

 its life ; assuming, in each of its three successive trans- 

 formations, a form wholly dissimilar to that with which 

 it was previously invested. 



We will proceed to trace the changes which it under- 

 goes, commencing with the egg, which is about the size 

 of agrain, and of a yellow colour, when fresh ; but after a 

 few days, become rather dark, of a bluish cast. The 



formed for covering it while it continues in the 

 aurelia state ; and several of these, properly 

 wound off, and united together, form those 

 strong and beautiful threads which are woven 



period which the egg requires is dependent on the tern- 

 perature of the climate; so much so, that some eggs my 

 be preserved during the winter and spring ; or they may 

 be quickened by artificial means, when the natural food 

 appears in sufficient quantity for their support. 



When hatched, it appears as a black worm, about a 

 quarter of an inch in length, gradually becomes larger 

 and whiter, and in about eight days its head enlarges 

 and it is attacked by illness, which lasts for three days ; 

 refusing food, and remaining in a state of lethargy. This 

 illness is supposed to be on account of the smallness of 

 the skin. The worm appears at the end of the third day 

 much wasted, and throwing off a kind of humour, which 

 has exuded between its body and the skin about to be cast 

 off, at the same time emits from its body silken cords, so 

 as to fasten the abandoned skin to a spot whilst the insect 

 forsakes it, which it performs in the following manner. 

 It first rubs its head among the leafy fibres, so as to dis- 

 encumber itself of the scaly covering, and then breaks 

 through that part of the skin nearest the head. Tin's 

 action causes the larva very great exertion. Soon after- 

 wards, it disengages its fore feet, and then the body is 

 quickly drawn from the skin, which remains stationary. 

 This operation occupies two or three minutes. The insect 

 then begins to feed with renewed vigour and health. The 

 skin sometimes refuses to separate from the body; in 

 which case, the pressure occasions swelling and inflam- 

 mation, and generally terminates in death. 



Those worms which have recently shed their skin, aro 

 easily known from the others, by the pale colour and 

 wrinkled appearance of their new skin. The larva 

 changes its skin five separate times ; and, on each oc- 

 casion, increases in size and weight, as may be seen in 

 following table. 



Inches, 



When born . J 



( )ne moult . I 



Two . . I 



Three . . IJ 



Four . . 2 



Five . 2J to 3 



Thus, in the space of a few short weeks, the worm in- 

 creases in weight more than nine thousand times. 



The annexed figures represent the worm iu its last 

 stage, the chrysalis, and the cocoon. 



Takp to an ounce. 



54,526 



3,840" 



610 



144 



35 



6 



The caterpillar, having arrived at its last moult, de- 

 vours its food most voraciously, and for ten days continues 

 increasing in size ; so that its structure can be better ex- 

 plained than in its former stages. It is now about three 

 inches in length, and is composed of twelve membranous 

 rings ; the head is scaly, hard, and tapering ; the mouth 

 is horizontal ; it has sixteen feet, six of which are placed 

 in front, armed with claws, on the three rings nearest to 

 the head ; the other ten feet are placed behind, eight of 

 which are on the sixth to the ninth and two on the Ic.st 



