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had never been covered by our operations, and to this we consequently 

 gave principal attention. Our most important spring preparations 

 covered all or the greater parts of the counties of Pike, Scott, Mor- 

 gan, Sangamon, Christian, Green, and Fayette, and much of the coun- 

 ties of Jersey, Madison, Macoupin, Bond, St. Clair, Montgomery, and 

 Shelby. By all the agencies and devices which we had found useful in 

 previous years, the people of this territory were notified, advised, in- 

 structed, and assisted. Public meetings were held at which the facts 

 were set forth and the plan of operations was outlined ; leading farm- 

 ers, grain dealers, and others influential and widely known among the 

 farming population were interviewed ; illustrated posters were put up 

 in post-offices and other places of general resort ; and many thousand 

 circulars were distributed by mail. 



At the end of the season data were collected for a careful estimate 

 of the results of the work. By a general inquiry made of those who 

 had handled supplies in the counties of Montgomery, Christian, San- 

 gamon, Menard, Macon, Morgan, Scott, Pike, Adams, Jersey, Ma- 

 coupin, Greene, and Madison, it was learned that not less than 2000 

 barrels of creosote and 1000 barrels of coal-tar had been used, to- 

 gether with considerable quantities of kerosene and salt. Further 

 inquiry enabled us to learn the average amounts of these substances 

 actually used per mile of barrier, and by this means to ascertain the 

 total length of barrier made and maintained for the season, and the 

 total cost of the same. All uncertain items of the computation were 

 estimated at the lowest reasonable figures. "We were thus assured that 

 at least fifteen hundred miles of barrier had been kept up in these 

 counties between fields of infested wheat and adjacent fields of corn, 

 at a total cost, for both materials and labor, of not more than $40,500. 



To learn what area of corn was actually protected by these bar- 

 rier lines, it was necessary to know the size of an average central Illi- 

 nois corn-field. Fortunately, a series of observations made for me by 

 two assistants engaged in a survey of the bird life of the state in 1907, 

 gave me this information. In crossing the state from Wabash to 

 Quincy, they traveled 71.87 miles through 362 corn fields, an average 

 of 63.53 rods for each field. Virtually all central Illinois corn-fields 

 being rectangular, the average form of a sufficient number is that of 

 a square, and the average size by the above data is 25.2 acres. In 

 other words, our fifteen hundred miles of chinch-bug barrier had 

 protected from invasion the equivalent of a belt of corn fields 63.5 

 rods wide and fifteen hundred miles long — an area of 190,590 acres. 

 The average yield of corn per acre in ten central Illinois counties not 

 infested by chinch-bugs in 1914 was 30.8 bushels. It was the best 

 judgment of my field assistants, supported by that of well-informed 

 farmers, that 25 bushels per acre was a very moderate estimate for the 

 yield of the protected corn-fields, and it was also the general opinion 

 that at least a fourth of this yield was due to measures of protection 



