88 
INTRODUCTION TO 
or of taking food. But although this is the general 
condition of pupa, it is by no means universally so ; 
many scarcely differ in appearance from their larvee 
and are equally capable of moving about, and equally 
voracious. This affords a convenient means of sepa- 
rating them into two great divisions, the one compre- 
hending such as resemble their larvae, the other 
those which bear no resemblance to their larvae. To 
the first of these divisions belong all those pupae which 
Linnaeus called complete , viz. the Orthoptera, Hem- 
iptera, (with some exceptions,) and certain tribes 
among the Neuroptera. The principal perceptible 
difference between these pupae and the perfect in- 
sects consists in the wings not being fully deve- 
loped ; but these organs approach gradually to a 
state of greater maturity with the age of the pupa, 
although without breaking through the case that con- 
tains them. The general form of the body, and the 
organization of the mouth, are similar in both states, 
the other differences besides the one indicated, 
when such exist, being confined to the legs or certain 
other parts of structure which are of utility to the 
pupa when it differs in its economy, as sometimes 
happens, from the imago. Thus the pupa of Cicada 
has the forelegs greatly thickened and adapted foi 
digging, because in that stage of its life it lives be- 
neath the ground ; after undergoing its final change 
it frequents trees, and the fossorial legs, being no 
longer useful, disappear. The respective states 
of larvae and pupa in the tribes in question being 
not indicated by any marked character, it is often 
