OBJECTIONS ANSWERED. 31 



roots of the grass, which being pulled up by the rooks 

 that devour this mischievous grub, these birds had been 

 mistaken by the tenant for the cause of the evil, and the 

 rags were placed to frighten away his best friends. On 

 inquiry why he had set up these sticks, he replied, " He 

 could n't beer to see'd nasty craws pull up all'd gess, and 

 sae he'd set'd bairns to hing up some aud clouts to flay 

 'em away. Gin he'd letten 'em alean they'd scan hev 

 reated up all'd close." Nor could I convince him by all 

 that I could say, that the rooks were not the cause of the 

 evil. Even philosophers sometimes fall into gross mis- 

 takes from this species of ignorance. Dr. Darwin has ob- 

 served, that destroying the beautiful but injurious wood- 

 peckers is the only alternative for preventing the injury 

 they do to our forest-trees by boring into them a ; not 

 being aware that they bore only those trees which insects 

 have previously attacked, and that they diminish very 

 considerably the number of such as are prejudicial to our 

 forests. 



From these facts it is sufficiently evident that entomo- 

 logical knowledge is necessary both to prevent fatal mis- 

 takes, and to enable us to check with effect the ravages 

 of insects. But ignorance in this respect is not only un- 

 fit 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 indigenous, but 

 have been imported. It was thus that the moth (Gal- 

 leria Mellonella) so destructive in bee-hives, and the as- 

 paragus beetle (Lema Asparagi) were made denizens of 

 Sweden 5 . The insect that has destroyed all the peach- 

 trees in St. Helena was imported from the Cape : and at 

 * Phytologia, 518. b Fn. Suec. 567, 1383. 



