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: the other hand, although its worst mischief coincides with that of the 
_ wireworms, it is not commonly the case that both are especially inju- 
rious in the same fields, the wireworms following grass of the first and 
second year preceding, and the plant louse most commonly infesting 
corn on old corn ground only. As lands recently in grass are most 
likely to contain the white grubs also, it is not a common thing to find 
the corn root aphis early in the spring in grub-infested fields. 
Its life history is now probably very well understood, but thorough- 
ly effective remedial measures, I regret to say, are not yet certainly 
known. Rotation of crops will often oreatly decrease or even prevent in- 
jury by dispersing the attack, but we have no conclusive proof that this 
measure diminishes to any considerable extent the number of root. lice 
in the country during any one year. It is therefore probable that this 
insect is increasing slowly in average numbers from year to year, and 
it may yet bring serious disaster to agriculture throughout the whole 
region best adapted to the culture of Indian corn. 
Although I have no data for a precise account of its distribution, 
it has been recognized by us in all parts of the State from Cairo to the 
extreme northern limit, and has been definitely reported outside Illinois, 
from Maryland, New Jersey, Indiana, Ohio, Kentucky, Minnesota, and 
Nebraska. It is altogether likely that it occurs in larger or smaller 
numbers throughout the whole corn belt. 
INJURY TO CORN. 
The corn root louse is a suctorial insect, taking only fiuid food 
through a stiff beak, which it thrusts into the tissues of the plant it 
feeds upon, producing thus no external injury, nor, indeed, any local 
internal effect discoverable by ordinary methods of observation. Indi- 
cations of injury by this insect are consequently all of a general char- 
acter, affecting the entire plant, and do not materially differ from those 
caused by severe drouth, except in the fact that they are likely to be un- 
equal in different parts of the same field in a way to indicate no con; 
nection with the amount of retained moisture in the soil. 
A noticeably greater abundance in early spring in the lower parts 
of an infested field seems to be due to the greater abundance there of 
young weeds on which the corn root aphis feeds at first. As soon as the 
corn starts to grow it may become infested, and even be killed outright 
before it appears above ground. We have, ‘in fact, found the root louse 
on the plant as early as May 9, only four days after the field was planted. 
The dwarfing of the plant, especially in patches here and there, 
with a yellowing or reddening of the leaves—beginning of course with 
the lowest ones—and a general apparent lack of thrift and vigor, are 
sufficient to cause suspicion of injury by this louse, a suspicion which 
will be confirmed in part if numerous burrows of ants are seen in or 
near the hills of corn. The presence of ants in the field may be over- 
looked after the ground has been recently cultivated, but can scarcely 
escape attention shortly after a rain, when these little insects actively 
open up their burrows, heaping up the little pellets of earth about the 
openings of their nests. 
