38 ASSOCIATION OF ECONOMIC ENTOMOLOGISTS, 



and more rapid distribution of the attack on corn. We must evi- 

 dentW find something- better than this, or something additional to it, 

 at least, if we would get nn etfective control of this dangerous pest. 



Treatment of the seed with kerosene or turpentine before planting 

 comi^letely protects the 3^oung plant for several weeks, the odor of 

 ihese substances persisting in the ground for a surprising time, but 

 unfortunately this treatment often seriously injures the young corn 

 itself — just why and under what conditions I have thus far been 

 entirely imable to make out. At any rate, the results are so uncertain 

 and so unaccountable tliat I tliink the method much too dangerous 

 for general use. 



Much the most promising and successfully preventive method is 

 such 'a management of the soil, in fall or winter or early spring, as to 

 break up and scatter the nests of the ant and to disperse their con- 

 lents — the ants and their young and the aphides and their eggs — 

 again and again through the dirt, destroying, at the same time, the 

 young vegetation as fast as it springs up. Thus ants and aphides 

 may be starved together, or, at the worst, the ant may escape from the 

 fields, leaving the scattered and buried aphides behind to perish. 



As a test of this method, I carried on various experiments in the 

 spring of 1904 and 1905 in several selected localities in ditferent parts 

 of Illinois, giving to a part of each infested field the usual spring 

 treatment as a preparation for corn, and giving to the remainder a 

 special additional treatment wdiich stirred the earth deeply and re- 

 peatedly and mixed it up thoroughly in the interval between the 

 earliest date for plowing and the usual time for planting corn. These 

 experiments may be summed up by saying that three times disking of 

 a badly infested field, previous to planting late in May, reduced the 

 ants and the aphides in the field by something over 92 per cent, and 

 the number of hills infested by each b}^ 64 per cent for the ants and 82 

 per cent for the aphides. Disking tw^ice in succession reduced the 

 number of insects by ()5 per cent for the ants and 84 per cent for the 

 aphides, and the nmnber of hills infested by each by 59 per cent and 

 75 per cent, respectively. The most remarkable effect was got by 

 disking once as soon as practicable after a heavy beating rain. This 

 reduced both ants and aphides by 90 per cent in the number of insects 

 and b}^ approximately 00 per cent in the number of hills infested. 



A PREVENTIVE ROUTINE. 



The general practical outcome of these observations and experi- 

 ments may best be given in the form of an agricultural routine for 

 the corn farmer whose crop is liable to injury by the corn root-aphis, 

 either because it is grown on land previously infested by that insect 

 or because of a general abundance of the aphis in his neighborhood. 

 Rapid rotation with an especially short period in corn, limited as a 



