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INTRODUCTION. 
many accidents through the influence of the elements, and 
they fall a prey to numerous animals, many of them also 
of the insect race, which, while they fulfil their own part 
in the economy of nature, contribute to prevent the undue 
increase of the noxious tribes. Too often, by an unwise 
interference with the plan of Providence, we defeat the 
very measures contrived for our protection. We not only 
suffer from our own carelessness, but through ignorance 
fall into many mistakes. Civilization, and cultivation, in 
many cases, have destroyed the balance originally exist- 
ing between plants and insects, and between the latter and 
other animals. Deprived of their natural food by the 
removal of the forest trees and shrubs, and the other 
indigenous plants that once covered the soil, insects have 
now no other resource than the cultivated plants that have 
taken the place of the original vegetation. The destruc- 
tion of insect-eating animals, whether quadrupeds, birds, 
or reptiles, has doubtless tended greatly to the increase of 
insects. Colonization and commerce have, to some extent, 
introduced foreign insects into countries where they were 
before unknown. It is to such causes as these that we 
are to attribute the unwelcome appearance and the undue 
multiplication of many insects in our cultivated grounds, and 
even in our store-houses and dwellings. We have no reason 
to believe that any absolutely new insects are generated or 
created from time to time. 'Flic supposed new species, made 
known to us first by their unwonted depredations, may have 
come to us from other parts, or may have been driven by the 
hand of improvement from their native haunts, where here- 
tofore the race had lived in obscurity, and thus had escaped 
the notice of man. 
To understand the relations that insects bear to each other 
and to other objects, and to learn how best to check the 
ravages of the noxious tribes, we must make ourselves thor- 
oughly acquainted with the natural history of these animals. 
This subject is particularly important to all persons who are 
