THEIR USES. 271 



certain periods of the year, in such prodigious 

 numbers, that no one, who has not been a witness 

 of the fact, would be capable of forming any idea 

 of it. We must not suppose that these vast 

 quantities of insects are permitted to exist without 

 some important and useful purposes having to be 

 performed by them. In the forests referred to, 

 vegetation is not only exceedingly rapid, but the 

 decay of it is equally so. Large trees, also, are 

 thrown down by hurricanes or other causes, to 

 which parasitical plants have clung. Forests, 

 therefore, would become almost impassable, both 

 for man or beast, and the atmosphere would be 

 rendered most hurtful to them, if the decaying 

 vegetable matter was not quickly consumed by 

 myriads of insects. Notwithstanding all the re- 

 searches of naturalists, and they have been great 

 and indefatigable, the varieties of Beetles alone are 

 so exceedingly numerous, that Mr. Darwin, in his 

 " Researches in Natural History," says that it is 

 sufficient to disturb the composure of an entomo- 

 logist's mind to look forward to the future dimen- 

 sions of a complete catalogue of these insects. It 

 is also an interesting fact, that carnivorous beetles, 

 and insects that feed on flesh, are very rare in 

 these forests, while they abound in places where 

 animals are very numerous. Mr. Darwin, in his 

 agreeable and valuable work above referred to, 

 states, that a person on first entering a tropical 



