INTRODUCTION. 1x 
ground, while others—the Caterpillar of the Great Swallow-tail Butterfly for instance—is fur- 
nished with a fork-like appendage near the head, from which it can emit at pleasure a foetid 
odour, which has doubtless the virtue of proving very disagreeable to a certain class of enemies. 
The enemies of Caterpillars are not only many tribes of birds, of which they form the chief 
summer food, but also a class of insects, the Ichneumon tribe, who deposit their eggs beneath the 
skin of the Caterpillar, by means of a sharp instrument or ovipositor with which they are 
furnished for that purpose. The eggs of the Ichneumon are hatched by the heat of the Cater- 
pillar’s body, and the young larvee of the Ichneumon feed upon the fatty substances within the 
devoted Caterpillar’s body, taking care to avoid a vital part. When these parasitic larvee arrive at 
their full growth, they form their cocoons, and undergo their change to little Chrysalides within 
the body of their victim, which, under these circumstances, generally perishes about that period. 
The growth of the Caterpillars of Butterflies is very rapid, and they cast their skin several 
times before arriving at their full growth, which in some instances, as in that of the common 
Butterfly known as the Silver-washed Fritillary, is in fourteen days. 
Caterpillars are of no sex, though, as in the case of the eggs of birds, a certain portion, no 
doubt, are so pre-organised as to become males in the perfect state, and others females. 
Tt was not till so recently as the end of the seventeenth century that the true nature of the 
progress from the larva to the perfect insect was known. At that period the invention of the 
microscope, combined with other causes, led to those scientific investigations which have been 
the means of unravelling the mystery of what seemed positive metamorphoses, but which now 
only appear successive steps of regular development. Swammerdam, among the foremost of a 
phalanx of indefatigable investigators, discovered, beneath the skin of the Caterpillar, all the 
embryo forms of the perfect insect, which become more and more palpable as the Caterpillar ap- 
proaches its full growth. In the course of these minute dissections he discovered even the future 
wings, spirally folded in a singular and beautiful manner, and also the long antenne and pro- 
boscis of the Butterfly, which were closely packed against the inner front of the head. The 
eventual legs, though so different in form, were also found, encased within the six pectoral legs 
of the Caterpillar. The skin of the Caterpillar is therefore little more than a second egg shell, 
and the Caterpillar, a creature become a walking egg, as it were, after having been within one 
that was motionless. 
The strictly external members of the Caterpillar may therefore be considered in the light 
of a kind of disguise, and Linnzus, taking this view of the subject, gave the name of larva, a 
Latin word meaning a imask, to this stage of the development of insect life. It is indeed a very 
happily selected and characteristic term, by means of which the stage of insect development, 
which follows that of the egg, is now universally expressed. 
The English term “ Caterpillar” is not perhaps so ingenious and characteristic as the one 
invented as a scientific definition by Linneus, but its origin is yet worth describing. In the 
earlier stages of the English language, cafes, or cafe, was a common term for provisions or deli- 
cacies of any kind, and was applied in that sense to garden herbs, or culinary vegetables : if to 
this we add the old Anglo-Norman verb piller, Anglicised to pill,* we obtain for the larva of the 
Butterfly the highly descriptive title of cate-piller, euphonised Caterpillar, that is, plant pillager, 
or destroyer. J 
The chrysalis is not formed till the larva has attained its full growth. At this period the 
Caterpillar, instinctively aware of the coming change, ceases to feed, quits the scene of its devas- 
tations, and seeks some spot of safety in which it may undergo its transformation, and remain 
securely in its semi-dormant state till the proper time for the final change, when the perfected 
insect is to issue from the shell of the chrysalis in all the completeness of its winged and final 
* From which we have still—pillage, pilfer, &c. 
