periment with different treatments of the soil previous to planting as 

 affecting subsequent infestation by ants and aphids. Studies of the 

 eft"ects of repeated deep stirring of the soil on the movements of the 

 ants under ground were also carried on by continuous observations 

 made at night. 



6. Laboratory experiments made by Mr. M. C. Tancjuary, at Ur- 

 bana, with ants exposed to various repellent substances with a view to 

 the selection of those repellents for use which proved to be the most 

 repulsive to the ants for the longest time. 



1910 



7. Field experiments near Galesburg, Knox county, made by G. E. 

 Sanders and W. P. Flint, with various repellents mixed with fertilizers 

 to be dropped with the corn by means of a fertilizer-dropper. Experi- 

 ments were also made with the cultivation method varied to include 

 heavy rolling of the soil after deep disking as a preparation for the 

 planting of corn. 



Effect of a Wet Planting-Time on the Action 

 OF Repellents 



A better example of the effects of weather upon a root-louse in- 

 festation of corn could scarcely have been devised than the contrast 

 between the seasons of 1906 and 1907, the former having been a rather 

 dry spring with rather high temperatures at our points of observation 

 and experiment, and the latter, an unusually wet one in May and 

 June, with low average temperatures, especially in April and May. la 

 May and June, 1906, both ants and root-lice in the fields we used were 

 at their best, while in 1907 the root-lice almost disappeared from the 

 worst-infested fields in May. These differences of weather worked an 

 even greater dift'erence in the effects produced on these insects by a 

 treatment of the seed with repellent substances like oil of lemon and 

 kerosene. In the dry spring of 1906, ants and plant-lice were kept out 

 of treated hills for a considerable time, to the great advantage of the 

 crop, while in the wet spring of 1907 there was most commonly no 

 difference between the treated and untreated plots in respect to the 

 number of ants and root-lice which they contained. 



A still more important fact was disclosed by a large-scale field ex- 

 periment made by the Bloomington Canning Co., to the effect that if 

 frequent rains follow upon the planting, heavy damage may be done 

 to the seed itself by the oil of lemon or kerosene treatment, altho 

 the ants and root-lice may not be appreciably disturbed by these repel- 



