56 INSECTS INJURIOUS TO STAPLE CROPS. 



A log or block should now be dragged through this strip 

 in such a manner as to form a deep furrow, with tlie incli- 

 nation of its side next the corn as steep as possible. In 

 attempting to climb this barrier, the dust will slide from 

 under the bugs and large numbers of them will accumulate 

 in the furrow, where, on a clear day, they will soon be 

 killed by the heat if the temperature of the air be over 

 88 degrees Fahrenheit (the soil will then be 110 degrees 

 Fahr.). The furrow may be kept clean by redragging the 

 log through it as often as necessary. If the weather be 

 cooler, the bugs should be further trapped by sinking holes 

 with a post-hole digger about one foot deep every ten or 

 twelve feet i]i the furrow. Large quantities will soon 

 accumulate in the holes, and may be there crushed or 

 killed with coal-tar or kerosene. 



Of course a sudden dash of rain will destroy such a 

 furrow, and the bugs will then at once march on to the 

 corn-field. In such an emergency a narrow strip of coal- 

 tar, about the size of one's finger, should be run around 

 the field a few feet inside the former furrow, with post- 

 holes dug as before upon the outside of the line. Dislik- 

 ing the smell of the tar, the bugs will again fall into the 

 traps and may then be destroyed. As many strips may 

 be made along the outer rows of corn as seem necessary to 

 prevent their further progress. These strips of tar should 

 be freshened whenever dust, straw, or rubbish has crossed 

 them at any point. In this manner one Illinois farmer 

 protected over 300 rods with less than a barrel of tar. 

 That this method is practicable and efficient was 

 thoroughly demonstrated by Prof. W. G. Johnson in a 

 series of experiments in Illinois, in the report of whose 

 work Prof. Forbes says: "In short, the success of this 



