1356 ARBORETUM AND FRUTICETUM. PART III. 
to Count Dandolo, a hundred trees, great and small, will furnish 7,000 Ib. of 
leaves, and these will be sufficient for 200,000 silkworms. 
Management of the Silkworm. The silkworm is the popular name for the larva, or caterpillar, of 
the moth known toentomologists as the Bombyx mori Fad. ; a native of China, which was introduced 
into Europe, as we have before seen, in 550. I%g. 1224. 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; d 
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 3in. 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 Covent 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 imperfect. They are preserved in a cool place, that is, in a temperature of from 10° to 12° 
Réaumur (55° 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 fastas 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 
is passed in 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 
two’s apparent sickness and want of appetite in the insect, which becomes torpid before the change 
of its skin takes place. During the whole period of the silkworm’s life, the litter made by the waste 
leaves, &c., must be frequently removed, the insects being attracted to one corner of their shelves with 
some fresh leaves, while the other parts arecleaned. When the caterpillars cease to eat, and run to and 
fro, frequently looking up, it is an indication that they are preparing to make their cocoons. They 
will now have become transparent, of a clear pearly colour, and the green circles round their bodies 
will have assumed a golden hue. Twigs of oak, tufts of dandelion, rolled up shavings from the 
cabinet-maker, cornets 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 
or shelves having been previously cleared of all litter, and the branches, or other materials, having 
been so arranged as to give the insects a feeling of security. They then immediately begin to make 
their cocoons, which are exuded in threads from the mouth, and which are generally completed in 
from four to seven days. When the insects have done working, the cocoons are taken from the 
twigs, and sorted : those that are double, or in any way imperfect, are thrown aside ; a certain num- 
ber are selected to breed from, and the rest are set apart for reeling the silk. ‘The first operation 
with these last is to kill the insects enclosed. This is performed, in Italy, by exposing the cocoons to 
the heat of the sun for three days, from 10 o'clock a, mM. to 5 0’ clock p. M., when the thermometer 
stands at 88° Fahr. In France they are put intobags or baskets, and enclosed for half an hour in 
ovens heated to 88°; but in America they are generally placed in sieves or boxes, having perforated 
bottoms; these are covered very closely with a woollen cloth, and then placed over the steam 
either of boiling water, or boiling whiskey or rum. (See New York Farm., vol. vi. p. 227.) The in- 
sects being killed, and the cocoons cleared of the external floss (which is manufactured under the 
name of floss, or spun, silk), they are thrown by handfuls into basins of pure soft water, placed over 
small furnaces of charcoal fires. When the water is almost at the boiling point, the cocoons are sunk 
with a whisk of broom or peeled birch under water for two or three minutes, to soften the gum and 
loosen the fibre. ‘This, however, is unnecessary when they have been killed by the steam of boiling 
