160 BIOLOGICAL PROBLEMS 



the destruction of our food crops by birds and insects 

 is an act of God, to which there is no available counter- 

 action in the hands of man. But although at the 

 present time we have no effective protection against 

 the ravages of the most prevalent bird and insect 

 pests, the wonderful results obtained by skilled 

 scientific investigation, particularly in the United 

 States of America and in Canada, encourage us to 

 believe that if we can only bring to an end our long 

 national neglect of science, the destruction of food 

 crops by our home-grown enemies may be, to a very 

 great extent, prevented. 



Of the two classes of animals the birds and the 

 insects which provide the farmer with his principal 

 destroyers, it might seem at first sight that the former 

 could be kept in check the more readily by the direct 

 method of attack, that is to say, by shooting the birds 

 and destroying their nests, and that the problem does 

 not present any insuperable difficulties. Some of our 

 birds, such as the wood-pigeon and the sparrow, 

 which feed almost entirely upon seeds and plants, are 

 regarded as being wholly destructive; other birds, 

 such as the tits, fly-catchers, martins, and others, being 

 insectivorous in habit, are regarded as wholly bene- 

 ficial. Every effort should be made, therefore, accord- 

 ing to prevalent views, to destroy the wood-pigeons 

 and sparrows, and to preserve and foster the tits, fly- 

 catchers, and the martins. But many of our most 

 common species are known to be omnivorous; they 

 will take grain, and they will destroy root-crops of 

 various kinds, but will also devour large numbers of 

 the most pernicious insect pests, and in these cases it 

 becomes necessary to determine by the evidence of 

 the food they have actually swallowed whether the 

 benefit they confer by the destruction of insects does 

 or does not exceed the damage they do to the seeds 



