114 PESTS OF GARDEN AND FIELD CROPS 
cluding cotton, squash, pumpkin, and strawberries. Plants badly 
attacked are stunted, lack color, and otherwise show that they are not 
making a healthy growth. Examination of the roots will then show 
large numbers of the lice. 
The corn root aphis is cared for, and is dependent on, colonies of ants. 
The latter are usually the common, small, brown ants of the species 
Lasius niger americanus Mayr. 
In winter the eggs of the aphis are cared for by these ants, who keep 
them in their nests, bring them out in the sunlight on warm days and 
carry them below frost line when the weather is severe. In spring the 
aphis eggs hatch, and the young wingless 
lice are carried by the ants to suitable 
weeds, the roots of which will form ac- 
ceptable food until the corn has sprouted. 
Thereafter the ants are in constant at- 
tendance on the lice, transferring them to 
the roots of corn when the latter become 
available. 
As warm weather comes on, the lice 
give birth to a second generation of living 
Fic. 78.—Larva of Crambus young, in which winged individuals: ap- 
luteolellus Clem. Slightly en- 
larged. Original. 
pear, and these migrate to new fields. 
Breeding goes on rapidly, the number 
of generations sometimes reaching a dozen in the course of the sum- 
mer. In the fall eggs are laid, and these are cared for again by the 
ants until another sea 
son. 
In control, the most important measure is to plow and harrow in the 
fall, so as to break up the nests of the ants. Keeping the fields clean of 
weeds will help materially, depriving the lice of food in the spring. 
Rotation is of value, since the first generation of the lice are wingless 
and by the time winged individuals appear corn will be sufficiently 
advanced to withstand attack from lice that fly in from other places. 
It is helpful, also, to keep corn growing vigorously. 
