26 



OBJECTIONS ANSWEKED. 



large proportion of the most noxious insects in every country- 

 are not indigenous, but have been imported. It was thus 

 that the moth (^Galleria Mellonella) so destructive in bee- 

 hives, and the asparagus beetle (^Crioceris Asparagi), were 

 made denizens of Sweden.^ The insect that has destroyed 

 all the peach trees in St. Helena was imported from the 

 Cape ; and at home (not to mention bugs and cock-roaches) 

 the great pest of our orchards, before mentioned, the apple 

 Aphis, there is good reason to believe, was introduced with 

 some foreign apple-trees. Now, extensive as is our com- 

 merce, it is next to impossible, by any precautions, to 

 prevent the importation of these noxious agents. A cargo 

 of wheat from North America might present us with the 

 famed Hessian fly, which some years ago caused such tre- 

 joidation in our cabinet ; but though introduced, the presence 

 of these insects, were Entomology a more general pursuit, 

 would soon be detected and the evil at once nipt in the bud ; 

 whereas in a country where this science was not at all or 

 little cultivated, they would most probably have increased to 

 such an extent before they attracted notice, that every effort 

 to extirpate them would be ineffectual. 



It is needless to insist upon the importance of the study 

 of insects, as calculated to throw light upon some of the 

 obscurest points of general physiology; nor would it be 

 difficult, though the task might be invidious, to point out 

 how grossly incorrect and deficient are many of the specula- 

 tions of our most eminent philosophers, solely from their 

 ignorance of this important branch of Natural History. 

 How little qualified would that physiologist be to reason 

 conclusively upon the mysterious subject of generation, who 

 should be ignorant of the wonderful and unlooked-for fact, 

 brought to light by the investigations of an entomologist, 

 that one sexual intercourse is sufficient to fertilise the eggs 

 of numerous generations of Aphides ! And how defective 

 Avould be all our reasonings on the powers of nutrition and 

 secretion, had we yet to learn that in insects both are in 

 action unaccompanied by the circulating system and glands 

 of larger animals ! 



1 Fn. Suec. 567. 1383. 



