816 INSECTA. 
but an imanimate half-formed mass, is now transformed into an anima 
decked with the most vivid colors, and rejoicing in its new existence. The 
operation of expanding their wings in by far the greater number of insects 
occupies only a few minutes; in some butterflies, half an hour or an hour; 
and some species of sphynx require several hours or even a day for this ope- 
ration. In certain t7pule and the ephemera, however, this process is almost 
instantaneous ; and in some species of this last genus, the insects, after be- 
ing released from the puparium, and making use of their expanded wings 
for flight, undergo a slight and further metamorphosis. They fix themselves 
by their claws in a vertical position upon some object ; withdraw every part 
of the body, even the legs and wings, from a thin pellicle which covered 
them like a glove; and so perfect is the resemblance of this exuvie to the 
insect, as to be at first sight mistaken for it. 
When the developement of the perfect insect is thus fully completed, it 
immediately begins to exercise its new powers in their destined functions. 
It walks, runs, or flies, in search of food, or of the other sex of its own spe- 
cies if it be a male, that the great purpose of its existence in this state may 
be fulfilled, the continuation of the species; and so unerring are its intuitive 
perceptions of the food which is proper, and the protection which it requires, 
that the new-formed being becomes at once a free denizen of the air, distin- 
guishing with more than botanical skill the plants and their juices which 
are necessary for its wants; and guided at once to results which in other be- 
ings are only acquired by the slow lessons of experience or education. The 
duration of insect life in the imago or perfect animal is subject to some vati- 
ations, but in general concludes when reproduction is perfected. There is 
not, as in the larger animals, a duration of a medium period, only liable to 
be shortened by accident or disease; but a conditional one, dependent on 
the earlier or later fulfilment of a particular function. The general law 
regarding this period among insects seems to be, that a few days, or at most 
a few weeks, after the union of the sexes, and the deposition of the ova by 
the female, both individuals perish. The period of effecting this is longer or 
shorter according to the species. Some, as several ephemera, live only a few 
hours, and never enjoy the enlivening light of the sun, appearing only to 
fulfil the great purpose of nature after sunset, and having finished this in the 
course of a few hours, by dropping their ova on the surface of their native 
waters, perish before the dawning of another day. Others, as flies, moths, 
butterflies, and indeed the greater part of insects, take a few days or weeks, 
to accomplish the same purpose. A comparatively small number, such as 
some of the larger coleoptera, orthoptera, &c., exist from six to nine, twelve, 
and even fifteen months ; and some instances have been recorded of particu- 
lar species, when kept and fed, having their existence prolonged considerably 
beyond this term. But these are exceptions to the general rule. And it is 
to be remarked further, that insect life seems to follow a different law from 
that which prevails among vertebrated animals, where the duration of 
