124 



these leaf-lice may become abuiKlaiit 

 enough to kill the leaves and to affect 

 to some extent the ^ealth of the plant. 

 The insect is, however, rarely seriously 

 inj\irious to corn, l)ut there is some 

 evidence, di-awn from - field observa- 

 tions of infested ears, that it may pre- 

 v(Mit the fertilization of the kernel by 

 sucking the sap from the silk and kill- 

 ing it before it has performed its func- 

 tion. Heavily infested corn-leaves turn 

 yellow or hmI, and may shrixcl and die, 

 particularly if the weather be dry at 

 the time. Hi-ooiu-corn is considerably 

 damaged by a redchMied discoloration 

 of the brush, due to a bacterial affec- 

 tion following upon the plant-louse 

 punctures. The growth of the brush 

 is also doubtless sometimes checked and the crop thus injured. In Texas 

 this insect has been found injuring barley as well as corn and sorghum. 

 The wingless form of this aphis is about 2 nun. long and half as wide 

 at the widest ]>art, the body being somewhat ovate in outline. The 



Fk;. H(>. The ('orn Rool-lou.so, Aphis 

 7>i(il(lirii(li('is, wiiiKless feiiiiile, sreutly eii- 

 larK<'<l. witli anteniui and tip of abdomen 

 more enlarged. 



Viv.. 117. The Corn Leaf-louse, Aphis muidis, winged female, greatly 

 enlarged, with antenna more enlarged. 



general color is pale green, with the cauda, cornicles, and the greater 

 ))art of the rostrum, anteniue, and legs black. The head is marketl with 

 two longitudinal dark bands, and tlie abdomen with a row of black 

 spots on each side and a black patch about the l)ase of the cornicles. 

 The latter are swollen in the middle, making the outlines convex. The 



