FARM METHODS FOR THE CONTROL OF INSECTS 37 



A few rows of wheat are often planted early in the fall as a trap 

 for the Hessian-fly, and as soon as the eggs are deposited they are 

 plowed under deeply and the later planting thus at least partly 

 protected. 



One of the most successful examples of averting injury by a 

 trap crop is the use of corn to lure the cotton boll worm and thus 

 prevent its injury to cotton. Corn is the favorite food plant of 

 this pest, which prefers to deposit its eggs on the silk and tassels. 

 By planting a few strips of late-maturing corn through the cotton 

 field, they will come into silk about the time the brood of moths 

 which normally deposit their eggs on cotton are flying and they 

 will lay them on the corn in preference, which should then be cut 

 and fed to stock. In this way by planting strips composed of sev- 

 eral rows planted at successive dates, the cotton may be almost 

 entirely protected. Possibly a modification of this method may 

 be applied for the protection of tomatoes or tobacco, though these 

 (;rops 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 then burning the tree. 



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.* 



The Use of Light-Traps. The destruction of insects by at- 

 tracting them to lights at night has always attracted attention. 

 Many such devices have been tried and several are now on the 



* 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. 



