103 



When so applied. No. 8 was somewhat more persistent than No. 7 ; 

 but No. 9 became hard enough at 80 degrees to bear the weight of a 

 chinch-bug, and it was not in perfect condition as a barrier until the 

 soil temperature reached about 100 degrees. Most of the other mixtures 

 tried were too fluid for the purpose, requiring from ten to forty-three 

 applications in the ten days. They were also liable to form a film on 

 the surface, enabling insects to cross even when the substance was still 

 soft beneath. 



As a result of these experiments, road oil No. 7 was the material 

 mainly used in all our operations against the chinch-bug in 1912. 

 (Figs. 5, 6, 7.) Especially recommended in a circular issued May 3, 

 and used in our own field demonstrations, it was brought into the in- 

 fested region in barrels by freight from Whiting in car-load lots and 

 everywhere accomplished the purpose intended. It had, however, two 

 rather serious disadvantages. It required for its successful use the 

 careful preparation of a hard smooth path upon which the oil could be 

 poured, and it was desirable that this pathway should be raised above 

 the general surface to protect it as far as possible from dust and other 

 objects likely to be blown upon it in a way to facilitate its passage by 

 the chinch-bugs. In extremely hot, dry weather the task of preparing 

 such a path in the hard dry earth was in some soils very difficult, and 

 in some almost impracticable. 



A more serious obstacle to success lay, however, in the fact that 

 road oil of the quality needed in the chinch-bug work was not wanted 

 or made for any other purpose, and that it must consequently be or- 

 dered some time in advance. Often the farmer would suddenly dis- 

 cover that his corn crop was endangered, was being already invaded, 

 perhaps, from a neighboring field of wheat, only to find that he must 

 wait a fortnight or more for relief; and by that time the mischief 

 would be done. Furthermore, as the place of manufacture was dis- 

 tant a hundred and fifty to two hundred miles from the infested terri- 

 tory, delays in transportation were frequently serious, large ship- 

 ments, altho called for in time, sometimes arriving after the emer- 

 gency for which they had been ordered had mainly passed. 



Failure of tlie 1913 Road Oil. — There was an oil refinery of large 

 capacity at Wood River, in Madison county, within the infested terri- 

 tory, and it seemed possible to avoid the worst of the difficulties just 

 mentioned by transferring the manufacture of road oil No. 7 from 

 Whiting to that place ; and in the spring of 1913 arrangements were 

 made to this end. This step proved, however, most unfortunate, for 

 reasons which we could not possibly have foreseen. The road oil fur- 

 nished from the Wood River refinery, altho made b}~ the same pro- 

 cess and containing the same percentage of asphalt as that from Whit- 

 ing, proved on delivery to have very different physical qualities, and 

 to be inferior even to coal-tar for use against the chinch-bug. Where 

 the Whiting oil would lie on a properly* prepared surface as a viscid 



