INTRODUCTION 7 
Bombycid moths, so well represented by tlie common silkworm. Many 
caterpillars bury themselves in the ground before becoming pupae; 
others lie on the surface, only drawing together a leaf or two by silken 
attachments ; some introduce particles of sand, earth, or wood into 
their cocoons, many hairy larvae even interweaving their own hairs ; 
and in others, again, a higher degree of protection is obtained by the 
abundance in the material of a hard-setting gummy secretion. In 
those cases where the pupa is wholly exposed (as in nearly all butter- 
flies), or is in the incomplete open-meshed sort of cocoon, there is no 
difl&culty in observing the changes in the form of the caterpillar prior 
to its last moult, which consist mainly in its contracting to much 
shorter, but at the same time thicker, dimensions, in the acumination 
of the abdominal region, and in the shrinkage and withdrawal from 
external projection of the head and legs. The abdominal pro-legs 
now finally disappear, and it is only in the last cast-ofl* skin of the larva 
that any record of their having existed remains. 
The caterpillars of Lepidoptera exhibit considerable variety in general 
form, those of several groups not presenting the ordinary sub-cylin- 
drical elongated shape so familiar to all in the silkworm, but being 
more or less widened, shortened, and depressed. Some have the skin 
smooth, while in others it is more or less roughened or granulated; 
and in a great number of others it is set with hairs, bristles, or spines. 
Among the hairy kinds there is immense diversity in the distribution 
and arrangement of the hairs, which are sometimes generally dispersed, 
but as often disposed in tufts, or springing from tubercles, or arranged 
in bands or local stripes and patches. Some of the more rigid and 
acute spines in the larvge of certain Bombycid moths are modified into 
weapons both defensive and offensive, being not only exceedingly sharp 
and serrated, so as to pierce and greatly irritate, but grouped in clus- 
ters or fascicles exsertible at the will of the animal. No other insect 
larvge approach caterpillars in beauty and variegation of colour and 
marking, whether we look to the smooth or hairy kinds. The few 
almost colourless or very dull-coloured caterpillars are those that live 
in the stems or at the roots of plants. The prevalent colour is green, 
and this is highly protective in concealing from their enemies creatures 
feeding almost entirely on leaves. But some of the most brilliantly 
variegated patterns of caterpillars are really protective in nature, as is 
well seen among the very large and beautiful larvge of the Hawkmoths 
(Sphingidce), where the stripes and spots of strongly-contrasted colours 
are adapted to the lights and shades, the outlines and tints, of the 
leaves, twigs, and buds of the plants the larvae frequent. Where this 
adaptation to surroundings does not prevail, it has been found in many 
cases that the gaudy, conspicuous caterpillars are unpalatable to birds 
and other insectivorous animals, and so are not liable to the persecution 
so generally experienced by their tribe. Some caterpillars of moths 
(Psychidce, and many of the Tincce) construct from the first a descrip- 
