INSECTICIDES AND GENERAL REMEDIES. 397 



interfering with the "balance of Nature" is always a serious prohlem, 

 and great caution, combined with intelligent forethought, should be 

 exercised. On the one hand we get certain animals preserved by 

 killing their natural enemies, but on the other hand we may have a 

 direful pest unexpectedly assert itself as the result of killing natural 

 enemies. 



References to Literature consulted. 



Board of Agriculture Leaflets, &c. 



Theobald, Fned. V. A Text-Book of Agricultural Zoology. Chiefly chapter 

 on the prevention and destruction of insect pests. 



