58 
economic significance, since the ant most active in preserving 
the plant louse species must be taken into account as a factor 
in toe economic problem. 
The Corn Root Aphis. 
(Aphis maidiradicis, Forbes.) 
(Plate VII., Fig. 5 and 6; and Plate VIII., Fig. 1-5.)* 
No insect affecting corn is more deserving of the attention of 
farmers and entomologists at the present time than the corn root 
aphis. It ranks as a corn pest with the chinch bug and the 
army worm, less injurious at any one time than these are 
locally and occasionally, but overtaking them, on the other 
hand, by its general distribution and the constancy of its at¬ 
tack. Although it lives upon the roots throughout" the life of 
^ e Plant, the principal damage is done at the same time as 
that caused by wireworms—while the corn is still small. It con¬ 
trasts with the corn root worms with respect to the time of its 
most injurious activity, the latter coming in at about the time 
when the aphis generally begins to loosen its hold; but the two 
agiee m the fact that they make their first appearance in sprint 
giound which has been in corn for at least a year pre¬ 
ceding. The common root worm is confined throughout the 
season to the field in which it hatches, while the a<phis presently 
scatters abroad, more or less freely according to the percentage 
of the second and succeeding generations which develop wings. 
On the other hand, although its worst mischief coincides with 
that of the wireworms, it is not commonly the case that both 
are especially injurious in the same fields, the wireworms follow¬ 
ing 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 
thoroughly effective remedial measures, I regret to say, are not 
yet certainly known. Rotation of crops wiil often greatly de¬ 
crease or even prevent injury 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 durin°’ 
any one year. It is therefore probable that this insect is in¬ 
creasing 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 distribu¬ 
tion, it has been recognized by us in all parts of the State from 
Cairo to the extreme northern limit, and has been definitely re¬ 
ported outside Illinois, from Maryland, New Jersey, Indiana, 
» vWinamus fema1e - ami of winded, windless, and pupa forms of 
' vlvl Parous female of this species, was published in the l?th Report of this office. 
