68 
INTRODUCTION. 
unsightly the otherwise umbrageous trees of the fo- 
rest, by consuming their leafy verdure. Almost their 
only employment, indeed, is to eat ; and so indus- 
trious are they at this agreeable occupation, that they 
often consume, in the course of twenty-four hours, 
double their own weight of food — a degree of vo- 
racity of which we find no example among the higher 
animals. Their structure is admirably adapted to 
their mode of life ; and their singular habits and eco- 
nomy render them even more interesting objects of 
observation in this preparatory state, than after they 
have assumed their more perfect and imposing form, 
when, 
No longer reptile but endowed with plumes, 
They through the blue air wander. 
The body of caterpillars is long and nearly cylin- 
drical, and is divided, by deep incisions, into twelve 
segments, exclusive of the head. The outer inte- 
gument, or skin, is usually membranous and soft, but 
in some instances it approaches more to a coriaceous 
texture. The general softness of the body is of 
great utility, as it thereby acquires great flexibility, 
and readily accommodates itself to the various curves 
and inflections which the insect is continually giving 
to it, and which are rendered necessary from the man- 
ner in which it obtains its food. Most of the cater- 
pillars that produce day-flying Lepidoptera, have 
sixteen legs, which are of two distinct kinds. Six 
of them are placed on the three anterior segments 
— that portion of the body which corresponds to 
