

ARBORETUM AND FRUTICETUM. 



1WRT III, 



to Count Dandolo, a hundred trees, great and small, will furnish 7,000 lb. of 

 leaves, and these will be sufficient for 200,000 silkworms. 



moment o/tkr Silkworm. The silkworm is the popular name for the larva, or caterpillar, of 

 the moth known to entomologists as the Zftmbyx m&rl Fab. ; a native of China, which was introduced 

 into Europe, as we have before seen, in 550, Fig. 1224k represents this insect, in its various stages, 



1224 



of the natural size: a, the eggs, which, when good, are of a pale slate or dark lilac colour; b 

 is the larva, or caterpillar, when full grown ; c is the insect in its chrysalis state, after the silk has 

 been removed ; d is the male imago, or perfect insect; and e, the female. When full grown, the 

 larva is nearly Sin. long, of a yellowish grey colour, with a horn-like process on the last joint of the 

 body. The eggs, in Britain, may be purchased in Covcnt Garden Market, at 10s. per oz. ; and care 

 should be taken that they are of the proper colour; because those that are of a pale yellow 

 colour are imnerfect. They are preserved in a cool place, that is, in -a temperature of from 10° to 12° 

 Reaumur [56° to 59° Fahr.), till wanted for use, and will retain their vitality upwards of a year. 

 To hatch them, a temperature of 86° Fahr. is required ; for which purpose, in most parts of 

 Europe where the silkworm is cultivated, the rooms used for that purpose are heated by stoves; 

 though in the East Indies, in the Islands of France and Bourbon, &c, and in the southern 

 parts of the United States, the natural temperature of the air is found sufficient. The houses in 

 which the insects are kept are built with numerous windows, for the admission of air; and fur. 

 nished with tables or shelves, on which the insects*are kept. These shelves have movable ledges, 

 of 1 in. or more in height, on each side, to confine the insects ; and several stages of them may be 

 formed one above the other, if care be taken that they are not attached to the wall, in order to admit 

 a free circulation of air on every side. When the mulberry begins to unfold its leaves, it is time to 

 commence the hatching of the eggs. These should be placed on the shelves in the temperature 

 mentioned ; and when they begin to turn white, which will be in about ten days, they should be 

 covered with sheets of writing paper, turned up at the edges, and pierced full of holes with a large 

 knitting needle. On the upper side of the paper should be laid some young twigs of mulberry, 

 which the insects will smell ; and, crawling through the holes in the paper, will begin to eat as soon 

 as they are hatched. As fast as these twigs become covered with insects, they are carefully taken 

 up and removed to another shelf, where they are placed on whity-brown or any absorbent paper, 

 about one to every square inch. The silkworm changes its skin four times before it spins its cocoon. 

 Its life is thus divided into five ages ; during the first of which it is fed with chopped or young 

 leaves, fresh ones being given as soon as it has eaten what it had before. At this time it frequently 

 appears to sleep, when it should on no account be disturbed. When the silkworm is in its second 

 age, it may be fed with young leaves entire, or old ones chopped small ; a great part of this age also 



; m' sleep. During the third age the silkworms become more lively and vigorous, and they will 

 devour full-grown leaves without cutting. In the fourth age the silkworm changes to a flesh colour, 

 and eats greedily. In the fifth age the silkworm will eat the coarsest leaves, and it should be fed 

 abundantly night and day, and have plenty of air and warmth. Each change is preceded by a day or 



;. parent sickness and want of appetite in the insect, which becomes torpid before the change 



of its -kin takes place During the whole period of the silkworm's life, the litter made by the waste 



leavi -, M\, mtut be frequently removed, the insects being attracted toonecorner of their shelves with 



some fresh leave-, while the other parts are cleaned. When thccaterpillarscea.se to eat, and run to and 



fro, frequently looking up, it is an indication that they are preparing to make their cocoons. They 



wifl now have become transparent, of a clear pearly colour, and the green circles round their bodies 



will have a-- mned a golden hue. Twigs of oak, tufts of dandelion, rolled up shavings from the 



ribinrt aanltfr. cornett Of paper, or sprigs of alaternus, phillyrea, heath, or broom, as may be most 



convenient, are then placed on the tables or shelves, to serve as a support for the insects ; the tables 



en previously cleared of all litter, and the branches, or other materials, having 



to give the insects a feeling of security. They then immediately begin to make 



. which are exuded in threads from the mouth, and which are generally completed in 



from four to seven day*. When the insects have done working, the cocoons are taken from the 



twigs, an'! lotted : ttlOM that an- double, or in any way imperfect, are thrown aside; a certain num- 



ted to breed from, and the rest are set apart for reeling the silk. The first operation 



with Um » kill the insects enclosed. This is performed, in Italy, by exposing the cocoons to 



t of the tun for three days, from lo o'clock a.m. to 5 o' clock p. m., when the thermometer 



i ahr in France they are put into bags or baskets, and enclosed for half an hour in 



but in America they are generally placed in sieves or boxes, having perforated 



covered wry closely with a woollen cloth, and then placed over the steam 

 ter, or boiling whiskey or rum. 'See Nrm )'/>/■/, l-'/u///., vol. vi. p. 227. ) The in- 

 led, and the cocoons cleared of the external floss (which is manufactured under the 



n, dk , the? are thrown by handful-: into basins of pure soft, water, placed over 



small furnaces o( charcoal fires. When tin water i lalmosl al tin boiling point, the cocoons are sunk 



ol broom or peeled birch under water for two or t line minutes, to soften t he gum and 



■ , < t, r < Thl , hoi ever, is unnecessar) when they have been killed by the steam of boiling 



