61 



2. Articles already published in the Twenty- fourth and Twenty- 

 fifth reports of the State Entomologist's office show marked benefit in 

 field experiments with deep plowing and repeated deep disking, and 

 also as a consequence of the treatment of seed-corn with oil of lemon 

 previous to planting, the last statement being based upon a single field 

 experiment made in 1906. Pages 4-6. 



3. List of operations described in this paper. Pages 6-7. 



4. Experiments of 1907 show that wet weather at planting-time 

 may either result in serious injury to the seed if repellents have been 

 applied to it direct, or in such washing away of the repellent sub- 

 stances that they produce no efit'ect either on the seed or on the ants 

 and aphids, the character of the effect apparently depending on the 

 amoiuit of rainfall and on its relation to the time of actual planting. 

 Comparative experiments show that the injurious effects reported 

 were not due, as at first surmised, to differences in the quality of the 

 repellants used in different operations. Pages 7-21. 



5. Laboratory experiments with a considerable variety of repel- 

 lents applied by uniform methods to colonies of the corn-field ant in 

 a special cage, showed that oil of tansy, oil of lemon, anise oil, tincture 

 of asafetida, apterite, and vermicide were very strongly repellent, that 

 kerosene, camphor, and coal-tar were less effective repellents, and that 

 a considerable number of other substances tested were, if repellent at 

 all, too slightly so to make them practically useful. Pages 21-41. 



6. Additional field experiments made in 1908, in a spring season 

 which proved to be very wet, resulted in no injury to the seed, and on 

 the other hand in no benefit to the crop, flooding rains apparently 

 washing away the repellents before they could take effect upon either 

 the seed-corn or the insects. Pages 41-44. 



7. Experiments made in 1910 with tincture of asafetida and oil 

 of lemon, applied first to bone meal which was then dropi)ed with the 

 corn by means of a fertilizer-dropper attachment to the planter, and 

 tested by the yield at corn-husking, showed a gain of 5.6 bushels per 

 acre by the use of asafetida, and 10.8 bushels per acre by the use of 

 oil of tansy, the first gain l^eing obtained at a cost for materials and 

 additional labor of thirty- four cents a bushel, and the second gain at 

 twenty-seven cents a bushel. This result was the more encouraging 

 since a very unfavorable spring caused an unusually poor stand and 

 reduced greatly the general yield of corn. In a good corn season the 

 gain would have been greater for the same cost. Pages 44-48. 



8. Additional experiments with deep plowing and repeated disk- 

 ing made in 1909 showed, in one case, a decrease, due to the treatment, 

 of 43 per cent in the number of hills infested by ants, and 18 per cent 



