19 
molt, we find that this ratio of win*ged forms is much greater in the 
badly infested hills; that the ratio of winged specimens increases, 
in other words, with the crowding of the insects and the conse- 
quent pressure on their food supply. In the 225 slightly infested 
hills were 225 wingless adults and 54 winged adults and pupae, a 
ratio of 21 per cent. ; while in the fifty badly infested hills were 227 
wingless adults and 349 winged adults and pupae, a ratio of 64 per 
cent, of the winged form. That is, the winged insects were three 
times as numerous in the crowded colonies as they were in the 
smaller ones. It is quite probable that experiment will show that 
this increase of the ratio of winged to wingless specimens might be 
brought about experimentally by various means which have the effect 
to diminish the average food supply. It is to be expected, conse- 
quently, that mere drouth, if it goes to the extreme of injuring the 
plant infested, may have the effect to break the force of the root- 
louse attack by stimulating the development of winged specimens, 
which, leaving the earth and flying abroad, would give the infested 
plant a chance to rally against injury. 
The Finnegan Bxperinient. (Table IV.). — On the farm of Ed- 
ward Finnegan, one and a half miles northeast of Bradford, a field 
of eighteen acres was selected for experiment. This field had been 
planted to corn in 1904, to oats in 1903, and to corn for the three 
preceding years. A considerable injury, apparently due to the corn 
root-aphis, had been noticed in it in 1904. Two parts of this field, 
which may be called plats A and B, were treated as follows : — 
Both were plowed April 18 to 21, disked May 22, harrowed 
May 23 and 24, and planted May 24. B differed from A only 
in the fact that it was twice disked in succession May 22, instead of 
once only on that date. Plat B was a strip running lengthwise 
of the field from north to south, and twenty-two rows wide, begin- 
ning on the west side; and plat A comprised the greater part of 
the field, extending eighty-eight rows inward from the eastern 
border. Smartweed and grass grew two or three inches high by 
May 22, heavy rains having by this time packed the soil very closely. 
The corn was put in about three inches deep, and began to show 
above the surface by May 30, on which date the first root-aphis was 
found in a hill of corn infested by Lasius alienus. These fields were 
examined June 9 for a test of the results of the single additional 
treatment with the disk harrow in which alone the two plats differed 
(see Table IV.). Fifty hills were examined from each plat, with 
the general result that in the check plat, A, seventy-five per cent, 
of them were infested by ants, and that in the experimntal plat, 
B, fifty per cent, of them were so infested. In the check plat, A, 
