78 
observed may nearly all have been due to a repellant effect ol 
the substances applied, in consequence of which the ants with¬ 
drew their charges deeper into the earth, with little diminutior 
perhaps of the injury to the corn. 
Breaking up Nests of Ants .—In one experiment, begun No vein 
ber 25, 1890, a strip of corn stubble three rods wide and ter 
rods long near the University premises at Champaign, was plowec 
six inches deep, half the strip being thoroughly harrowed also 
The ants’ nests among the corn hills were thus turned out and 
thoroughly broken up, except that in a few cases the plow did 
not go the full depth of the nests, but left the bottom undis 
turbed. The harrowing knocked the dirt out of the roots o\ 
the corn and broke up the fragments of the nests remaining ir 
the clods. April 18, 1891, when the ground was again plowed, 
five ants’ nests were found in this plot and thirteen in an equa 
strip beside it. All of these outside nests contained ant larva 
of various sizes, while those inside the strip contained no ants 
but worker adults. Ten of the former lot of nests and three o\ 
the latter contained root lice also, on smartweed roots. 
In another precisely similar experiment, begun upon the same 
day in an adjoining field, a strip was plowed two and a hall 
rods wide by twelve rods long, half of this being thoroughly 
harrowed, as before. The plowing averaged six inches in depth, 
but the plow ran considerably deeper under the corn rows, 
and the ants’ nests were well broken up and scattered. April 
17 of the following spring the ground was plowed for corn and 
thoroughly examined to determine the result of the experiment, 
The part which was harrowed contained three ants’ nests, the 
remainder six; while on an equal strip adjoining, thirty were 
found. None in the strip plowed in fall contained young ants, 
while everyone of those outside contained them. Several wingless 
females were seen in the nests, one of them in the plowed strip 
Neither the weather at the time nor that of the following win¬ 
ter was especially favorable to the success of such an experiment, 
the mercury reaching a maximum of 49° F. on the day the ex¬ 
periment began; and the winter following—that of 1890-91— 
being unusually open and warm. Further, there had been more 
than a week of warm spring weather previous to April 18, the 
mercury reaching 72° on the 9th, 75° on the 13th, and 77° and 
78° on the 17th and 18th respectively—temperatures at which 
ants as active as the little Lasius niger alienus might well dis¬ 
perse themselves and begin new colonies in unoccupied ground. 
These experiments afford, perhaps, scarcely a sufficient basis 
for a final conclusion as to the economic value of this method, 
but so far as they go they are most encouraging. If we com¬ 
pare the treated plots with the check plots beside them, we find 
(1) that the ants’ nests in the former were less than a third as 
many as in the latter; (2) that all in the plowed and harrowed 
plots were destitute of ant larvae while in the check plots, all with¬ 
out exception contained such larvae; and (3) that in the single 
