INSECTS INJURIOUS TO CORN. 



253 



The injury which this insect does is to extract the sap from the 

 roots of the corn plant, thus weakening the entire plant and causing it 

 to be stunted, or to make nubbins instead of a full ear. The injury 

 varies all the way from a scarcely appreciable effect to the complete 

 destruction of the corn plant. The complete destruction of the corn 

 plant, however, is very rare indeed, unless the work of this aphis be 

 supplemented by long continued drought. In fact, the work of the aphid 

 has the same effect upon the plant that a long severe drought has, they 

 simply extracting the sap, which amounts to practically the same thing 

 as the want of sufficient moisture in the ground would have upon the 

 plant; and when these insects are quite numerous and a drought occurs, 

 the plants, of course, suffer unduly and the crop may be entirely ruined, 

 provided a drought occurs as a supplement, which of itself would not 

 necessarily cause such an injury. It is the supplementing then of the 

 injury by the aphis which causes the serious trouble. 



The corn-root-aphis is recognized, I think, by all corn growers. 

 The insect affects the corn plant only upon the roots under ground, but 

 every corn grower has pulled up infested corn and observed these small, 

 bluish-green plant-lice, or aphids, sometimes occurring in large clusters 

 upon the roots. These insects can be found on the corn roots before the 

 corn is out of the ground, in fact, when the root first begins to appear 

 nicely from the seed, and they may be found upon the corn plant until it 

 is completely matured. 



The life history of this insect is interesting and can be briefly 



described as follows : The so-called winter eggs are fertilized eggs. 



They are deposited by the female aphids late in the fall. These eggs are 



oval, black and glossy, and, of course, 



quite minute. They may be found about 



the roots of the corn plant late in the fall, 



in the burrows of the little red ants that 



are so common in these situations. There 



are two species of these little red ants 



that one finds very numerous throughout 



the corn fields and other fields about the 



country (Lasius niger and Lasius niger 



alienns), which little red ants are our 



most common ants filling this description. 



A picture of one of these ants is given 



enlarged eight and one-fourth diameters 



in figure 12. This is a worker ant, and, Fig. 12.— Lasius niger aiienus, 

 c i-v i- ii t- 11 r ii • worker ant; enlarged eight and one- 



Of course, constitutes the bulk of the m- fourth diameters. 



