32 OEiECTIONS ANSWERED. 



From these facts it is sufficiently evident that ento- 

 mological knowledge is necessary both to prevent fatal 

 mistakes, and to enable us to check vk'ith effect the ra- 

 vages of insects. But ignorance in this respect is not 

 only unfit to remedy the evil ; on the contrary, it may 

 often be regarded as its cause. A large proportion of 

 the most noxious insects in every country are not indi- 

 genous, but have been imported. It was thus that the 

 moth (Tinea Mellonella) so destructive in bee-hives, 

 and the asparagus beetle {Lema Asparagi, F.) were 

 made denizens of Sweden^. The insect that has de- 

 stroyed 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 commerce, it is next to im- 

 possible, by any precautions, to prevent the importa- 

 tion of these noxious agents. A cargo, or even a sam- 

 ple, of peas from North America might present us with 

 that ravager of pulse, the pea-beetle {Bruchus Pisi. L.); 

 or the famed Hessian fly, which some years ago caused 

 such trepidation in our cabinet, might be conveyed here 

 in a ship-load of wheat. Leeuwenhoek's wolf (T««ea 

 granella, F.) might visit us, in a similar conveyance, 

 from Holland or France. But though introduced, were 

 Entomology a more general pursuit, their presence 

 would soon be detected, and the evil at once nipt in 

 the bud ; whereas in a country where this science v.'as 

 not at all or little cultivated, they would most proba- 

 bly have increased to such an extent before they at- 



* Fn. Suec. 567. VJS3. 



