17 



where no injury was done, for comparison with the Bloomington ob- 

 servations, and to that extent the proof must remain incomplete. 



FIELD EXPERIMENTS WITH REPELLENTS, I907 



I have next to report the purely negative results of a series of 

 field experiments and observations begun in April, 1907, at Le Roy, 

 McLean county, by one of my field assistants, Mr. E. O. G. Kelly, and 

 continued by Mr. John J. Davis, to whom the problem was transferred 

 in the latter part of June. In these experiments, intended as a partial 

 repetition and verification of those made at Elliott, in Ford county, in 

 1906,^ no injury was done to the seed by oil of lemon and alcohol, oil 

 of citronella and alcohol, carbolic acid, pure kerosene, or pure turpen- 

 tine, each applied in the proportions commonly used by us at this 

 time; nor was any difference discernible between experimental and 

 check plots in the degree of infestation by the ants or by the aphids. 

 Both the observers atttributed the results to heavy flooding rains 

 which fell at intervals during the whole planting-period, and which 

 washed away the fluid repellents so thoroly that the seed no longer 

 smelled of them. At the same time root-lice virtually disappeared 

 from fields which had been especially selected for experiment because 

 they were so heavily infested by ants before planting that it seemed 

 certain that the corn would be seriously injured by root-lice unless it 

 was artificially protected. Rains fell here, in short, at a time and in an 

 amount both to drown out the root-lice and to wash away the re- 

 pellents before the seed could be injured. 



The following is an outline of the more important of these ex- 

 periments. 



Experiment 1. — A field of thirty acres, on which corn was grown 

 in 1906, preceded by oats in 1905. The seed used in planting was 

 dealt with as follows: that for 16 rows, was treated with a fourth 

 of an ounce of kerosene to the gallon of seed; for 24 rows, with a 

 half ounce of kerosene to the gallon; for 68 rows, untreated and re- 

 served as a check; for 44 rows, treated with three-fourths of an ounce 

 of kerosene ; for 62 rows, with three ounces per gallon of a mixture 

 of oil of lemon (TO per cent) and alcohol (90 per cent) ; and for 10 

 rows, untreated, as an additional check. 



The field was planted on the 11th of May, 1907, and on the 20th 

 of May no odor of kerosene or oil of lemon could be detected on the 

 treated seed. On the 28th of May, many hills were burrowed by ants, 

 but an examination of fifty such hills, dug up for the purpose, dis- 



'25tli Rep. State Ent. III., p. 14. 



