INDIRECT BENEFITS DERIVED FROM INSECTS. 259 



from them all the unwholesome part of their contents. 

 This, Linne says, will easily appear if any one will make 

 the experiment by filling two vessels with putrid wa- 

 ter, leavino- the larvffi in one and taking them out of the 

 other. For then he will soon find the water that is full 

 of larvsB pure and without any stench, while that which 

 is deprived of them will continue stinking^- 



Benefits equally great are rendered by the wood- 

 destroying insects. We indeed, in this country, who 

 find use for ten times more timber than we produce, 

 could dispense with their services ; but to estimate them 

 at their proper value, as affecting the great system of 

 nature, we should transport oursel ves to tropical climes, 

 or to those under the temperate zones, where millions 

 of acres are covered by one interminable forest. How 

 is it that these untrodden regions, where thousands of 

 their giant inhabitants fall victims to the slow ravages 

 of time, or the more sudden operations of lightning and 

 hurricanes, should yet exhibit none of those scenes of 

 ruin and desolation that might have been expected, but 

 are always found with the verdant characters of youth 

 and beauty ? It is to the insect world that this great 

 charge of keeping the habitations of the Dryads in per- 

 petual freshness has been committed. A century al- 

 most would elapse before the removal from the face of 

 nature of the mighty ruins of one of the hard- wooded 

 tropical trees, by the mere influence of the elements. 

 But how speedy its decomposition when their opera- 

 tions are assisted by insects ! As soon as a tree is fallen, 

 one tribe attack its bark% which is often the most in- 



^ (Econ. Nat. Amcen. Ac. ii. 50. Stillingfleet's 2'racts, 122. 

 " Maupertviiu observes, that in Lapland he saw many birch-trees lying 

 on the ground, « hidi had probably been there for a very long time, with 



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