FARM METHODS FOR THE CONTROL OF INSECTS 41 



crops have never been thus protected from this insect to our 

 knowledge. 



Radishes are sometimes used as a trap crop for the root-mag- 

 gots which affect the roots of .cabbages and onions. The same 

 principle is sometimes used in combating forest insects by gird- 

 ling a tree upon which certain kinds of forest pests will concentrate, 

 and it is then cut and burned. 



These examples will suffice to show that very many of .the most 

 important insect pests may be largely controlled by simply adapt- 

 ing the general methods of farm management so as to avoid or 

 prevent injury by them. They indicate the importance of a 

 knowledge of the life history of any insect which is to be combated, 

 knowing which, some of the above or similar methods will often 

 suggest themselves as applicable. Such a control of insect life 

 through the practical use of natural agencies epitomizes the scien- 

 tific method in the art of agriculture; i.e., the most practical and 

 effective and yet simple methods based upon exact knowledge.* 



* See F. M. Webster, Farm Practice in the Control of Field Crop Insects, 

 Yearbook U. S. Dept. Agr., 1905, p. 465, and Some Things that the Grower 

 of Cereal and Forage Crops Should Know about Insects, Yearbook U. S. 

 Dept. Agr., 1908, page 367. 



