ORDER I[V.——MOTHS AND BUTTERFLIES. 181 
cellent silk, and of which extensive use will probably be 
made as soon as the young giant of North America arrives 
at maturer age. Of these I shall speak at length in some 
of the following pages. 
Various kinds of apparatus have been invented for the 
purpose of raising caterpillars, and the simplest kind are 
boxes, the bottom of which is covered with earth, and the 
top with gauze, so as to admit of fresh air at all times. In 
some places large cages, like those for birds, are used, 
which are also covered with gauze, and in which are placed 
the different plants upon which the caterpillars feed. This 
is a very convenient contrivance for observing their mode 
of living, the casting of their skins, and their metamorph- 
oses, as also for obtaining handsome and perfect specimens 
for the cabinet. They may be raised, however, in the same 
manner as silk-worms are generally raised, and which we 
shall presently describe. 
As soon as the cold of autumn deprives the trees and 
shrubs of their foliage all caterpillars disappear, either 
metamorphosing themselves into cocoons, or, if not yet 
ready for such a change, concealing themselves under the 
ground. In the following spring, as soon as the new leaves 
appear on the trees, they come out from their caverns in the 
hollow trees or the crevices of the rocks, and with a host of 
new ones that issue from the eggs which were deposited in 
the previous autumn, they commence their ravages, devour- 
ing all the new leaves and shoots within their reach. 
After the caterpillars have cast their skin several times 
and are full grown, they metamorphose themselves into an 
immovable cocoon (chrysalis, aurelia, pupa), which eats no 
more, and under the horny skin of which may almost al- 
ways be recognized the wings and other members of the 
future Butterfly or Moth. Many of these come out after a 
few ‘weeks, during the summer, again lay their eggs, from 
which proceed other caterpillars, which latter generally 
