THE DESTRUCTION OR MITIGATION OF 

 INSECT-PESTS 



Wherever vast quantities of the same plant are grown to- 

 gether, and especially where the same crop is grown year after 

 year on the same fields, an opportunity, quite unparalleled in 

 wild nature, is offered to vegetable - feeding insects, and no 

 ordinary ingenuity can perfectly defend plants reared under 

 such conditions. It is as if we created an immense vacuum, 

 and expected to prevent the air from making its way in. 

 No common precautions will prevent insects from multiplying 

 prodigiously whenever abundant food is provided for them, 

 and we must hope rather to check than altogether to stay their 

 ravages. 



German science, especially when it was a question of forest- 

 management, was long looked to for the best examples of 

 successful treatment of injurious insects. A large body of 

 scientifically trained men, devoting their lives to the study 

 •of injurious insects, could hardly fail to learn and record much 

 that is valuable in practice, and German books often contain 

 original and thorough investigations of insect devastations. In 

 other European countries the state of knowledge, for lack of an 

 expert class, is far inferior. In England we have the useful 

 book of Curtis on Farm Insects, but very nearly all the rest 

 is mere compilation. Here and there old knowledge has been 

 applied to new outbreaks, or a life-history has been Studied by 

 some isolated enthusiast, but the lack of scientific knowledge 

 and practical experience is lamentable. In the United States 

 and Canada, where the English indifference to scientific studies 

 still to a great extent prevails, a long series of disasters to the 

 crops has led to the adoption of a wiser policy. Trained State- 

 entomologists are now numerous in the United States, and 

 a national Department of Agriculture, served by officers who 

 possess both scientific and practical knowledge in a high de- 



237 



