20 
seventy-four per cent, of the hills were infested by root-hce, and 
forty-four per cent, in the experimental plat. The former con- 
tained 3034 ants per hundred hills, and the latter 1746 — fifty-seven 
per cent, of the first number. The latter, or check plat, also con- 
tained 2392 root-lice per hundred hills, and the former, or experi- 
mental plat, 1362 root-lice per hundred hills — sixty per cent, of the 
number in the first. 
More briefly stated, the single treatment with the disk harrow 
May 22, following immediately upon an earlier treatment the same 
day (see Experiment 4, Table V.), had reduced the infestation by 
ants by forty-two per cent, in number of insects and by thirty-three 
per cent, in number of hills infested ; and had reduced the infesta- 
tion by root-lice by forty-three per cent, in number of insects and 
by forty-one per cent, in number of hills infested, the result being 
tested by a critical examination made sixteen days after the field 
was planted. In short, a single disking of the soil had diminished 
the infestation by ants and root-lice generally by something over one 
third. 
Table IV. Abstract op Finneg an Experiment. 1905. 
(Plained Maj' 24: examined June 9.) 
Plat A 
Plat B 
♦Plowed (1), disked (2), 
harrowed (4) 
Plowed (1), disked twice (2, 3), 
harrowed (4) 
50 hills examined 
50 hills examined 
t 
Per cent. 
of 
hills infested 
Number of 
insects per 
hundred hills 
Per cent. 
of 
hills infested 
Number of 
insects per 
hundred bills 
Ants 
Aphids 
75 
74 
3034 
2392 
50 
44 
1746 
1362 
1. Plowed April 18 to 21. 2. Disked first time May 22. 3. Disked second time May 22. 
4. Harrowed Maj 23 and 24. 
Observations on the Barto Farm. — A field of seventy acres, 
forty-five in oats and the remainder in corn, on the farm of Mr. 
Frank Barto, near Bradford, 111., was selected for observation be- 
cause of the extraordinary abundance of ants' nests containing aphis 
eggs to be found in various parts of it, and because of the history of 
the oats fields with reference to corn preceding, and of one of the 
corn fields with reference to oats. It was the principal object of the 
observations here made, to ascertain the effect on the corn root-aphis 
of a change of crop from corn to oats. 
*See note to Table I., p. 105. 
