6 
SPECIAL BULLETIN NO. 8 
Fig. 4. Corn Root-Louse, Much Enlarged (Forbes) 
THE CORN ROOT-LOUSE 
The corn root-louse, or root-aphis, as it is sometimes called, is now recognized 
as a pest in Minnesota,. 
If young corn plants on old corn ground are retarded in growth and unhealthy 
in appearance, and particularly if the burrows of ants are numerous in or near the 
hills, it would be well to examine the roots for lice which can be recognized by their 
small size, oval form, and bluish green color slightly whitened with a waxy bloom. 
They feed by sucking the sap from the roots and in this way rob the plant of nour- 
ishment. While the resulting injury may be slight, in many cases there is a partial 
or total loss over areas of half an acre each. Dry weather following the attacks of 
the root-aphis prevents the plant from recovering and increases the injury. 
Life History 
The eggs of the root-lice are cared for in winter by ants in their burrows in the 
cornfield. After hatching, the young lice are placed by the ants on the roots of 
smartweed or foxtail grass from which they are later transferred to corn. They 
breed very rapidly and as they become crowded on the roots of one plant they are 
carried by the ants to fresh plants. From time to time winged individuals are pro- 
duced which fly to other parts of the same field or to other fields. There they are 
taken by the ants into the ground and placed on corn roots where they start new 
colonies. They secrete a sweet liquid upon which the ants feed. 
Methods of Control 
Since the corn root-louse works under ground it is out of reach of any effective 
method of treatment after it has attacked the corn. The corn grower must rely 
on prevention. 
The injury is never severe except in ground that has been planted to corn for 
several years in succession. A short rotation in which the field is not planted to 
corn for more than two consecutive years will prevent the root-lice from gaining a 
serious foothold. 
If it is necessary to plant corn on land that is known to be infested with root- 
lice, the ground should be plowed six or seven inches deep, and the soil thoroly 
stirred by frequent deep disking before planting-time. The plowing may be done 
in the fall or early spring, but the disking, of course, must be done in the spring. 
This treatment will break up the nests of the ants and scatter the eggs or expose them 
