drown out the root-lice and also, to some extent, the maggotlike young 
of the ants under ground ; and some fields heavily enough infested in 
April and early May of that year to make a profitable crop very un- 
likely, were completely cleared of root-lice by the beginning of June, 
and contained unusually few ants. 
Our later work on the ant-aphis problem has been done mainly on 
two lines. We have attempted to test, by field experiments, the value 
of a repeated deep and thoro stirring of the soil previous to planting, 
and we have experimented with ofifensive applications to the seed, of a 
kind to last a considerable time in the ground, and to keep the ants, 
and consequently the aphids, out of the hills as long as possible while 
the plant was still young and especially sensitive to injury. Experi- 
ments of the first class were reported in Bulletin 104 of the Agricul- 
tural Experiment Station published in October, 1905, and again in the 
Tweiity-fourth Report of the State Entomologist, pages 8 to 29 ; but 
those with repellents applied to the seed in 1905-06 are here fully re- 
ported for the first time. 
Repellent Applications to the Seed 
My attention was first called to the fact that applications to the 
seed might serve to protect young corn against root-louse attack by 
statements occasionally made by farmers who had treated their seed- 
corn with kerosene or turpentine just before planting.* Having, I 
must confess, very little faith in this treatment, I nevertheless directed 
an assistant, Mr. E. O. G. Kelly, in charge of my field work in 1905, 
to test the effect of kerosene used in this way, and as part of a general 
field experiment for the protection of corn against aphis injury, he 
planted a small plot in an experimental field with seed which had been 
soaked in kerosene for half an hour. 
The effect of this treatment was a double surprise to us. In the 
first place, only about half as much of the corn grew as in other ex- 
periments made in the same field with seed from the same lot, serving, 
consequently, as checks on this ; the other half swelled up with the 
moisture absorbed, but never sprouted. Furthermore, germination 
was delayed, growth of the young corn was slow at first, and many of 
the plants were dwarfed and crippled, the growing tip or plumule of 
the plant making its way with great difficulty out of the inclosing 
sheath (the coleophyl) which protects it as it grows upward thru 
the earth. In the second place, altho the field of corn of which this 
planting was a part was heavily infested and noticeably injured by the 
corn root-aphis, this special plot, when examined some weeks after 
planting, was found to be almost wholly free from the aphis, and to 
contain but few ants ; and at husking time its yield equaled in quan- 
tity and excelled in quality that of like areas in other parts of the same 
field. The treatment of the seed had evidently so repelled the ants 
*See especially nfy address on the corn root-aphis in the Tenth Report of the Illinois 
Fanners' Institute, p. 49. 
