446 
ON THE ORIGIN AND METAMORPHOSES OF 
INSECTS 
1 
THE CLASSIFICATION OF INSECTS 
AS many years ago the civil and ecclesiastical au- 
thorities of St. Fernando in Chili arrested a certain 
M. Renous on a charge of witchcraft, because he kept 
some caterpillars which turned into butterflies.* Most 
persons, however, are aware that the great majority of 
insects quit the egg in a state very different from that 
which they ultimately assume ; and the general statement 
in works on entomology has been that the life of an insect 
PLATE 1 
Pu. 1.t—Fic. 1, Cricket. 2, Earwig. 3,Aphis, 4, Scolytus. 
(Pt. 2.—Fic. 1, Larva of Cricket. 2, Larva of Aphis. 
7, Larva of Cynips. 
instance the common fly, acquire their full bulk in a form 
very different from that which they ultimately assume, 
and pass through a period of inaction in which not only 
is the whole form of the body altered, not only are legs 
and wings acquired, but even the internal organs them- 
selves, are almost entirely distintegrated and reformed. 
It will be my object to bring these changes clearly before 
you, and if possible to throw some light on the causes to 
which they are due, and on the indications they afford of 
the stages through which insects have been evolved. 
* Darwin's “Researches into the Geol 1 Hi: f th 
Countries visited by H.M.S, Beagle,” p. aa ia hae a ig 
NATURE 
5, Anthrax, 6, Balaninus. 7, Cynips. 
3, Larva of Earwig. 
8, Larva of Ant. 
[April 10, 1873 - 
may be divided into four periods. Thus, according to 
Kirby and Spence* “The states through which insects 
pass are four: the egg, the /arva, the pupa, and the — 
zmago.” : 
Burmeister,t again, says that, excluding certain very 
rare anomalies, “ we may observe four distinct periods of 
existence in every insect, namely, those of the egg, the 
larva, the pupa, and the imago, or perfect insect.” In 
fact, however, the various groups of insects differ very 
much from one another in the metamorphoses they pass 
through ; in some, as in the grasshopper for instance, the 
changes consist principally in a gradual increase of size, 
and in the acquisition of wings; while others, as for 
PLATE 2 
8, Ant. 9, Wasp (after Ormerod). * 
4, Larva of Scolytus. 5, Larva of Anthrax, 6, Larva of Balaninus. 
9, Larva of Wasp. 
The following list gives the orders or principal grou: 
into which insects may be divided. I will not indeed, 
as this is not a work on the classification of insects, enter 
into my own views, but have adopted the system given 
by Mr. Westwood in his excellent “Introduction to the 
modern Classification of Insects,” from which also, as 
a standard authority, most of the figures on Plates 
* Introduction to Entomology vi. p. 50. 
+ Manual of Entomology, p. 30. 
1 When not otherwise acknowledged, the figures on the first four plates 
are principally borrowed from Mr. Whetwood’s excellent ‘ Introduction to 
the Modern Classification of Insects.” 
