INSECTS INJURIOUS TO CORN 



171 



the tassel, and the upper part of stalks of corn, and more abun- 

 dantly and frequently on broom-corn and sorghum. Multiply- 

 ing in place by the birth of living young, which do not wander 

 from their place of origin, these leaf-lice may become abundant 

 enough to kill the leaves and to some extent to effect the health 

 of the plant. The insect is, however, rarely seriously injurious 

 to corn, but there is some evidence, . . . that it may prevent the 

 fertilization of the kernel by sucking the sap from the silk and 

 killing it before it has performed its function. Heavily infested 

 corn leaves turn yellow or red, and may shrivel and die, partic- 

 ularly if the weather be dry at the 

 time. Broom-corn is considerably 

 damaged by a reddened discoloration 

 of the brush, due to a bacterial affec- 

 tion following upon the plant-louse 

 punctures. 



" The wingless form of this aphis 

 is about 2 mm. (one-twelfth inch) 

 long and half as wide at the widest 

 part, the body being somewhat ovate 

 in outline. The general color is pale 

 green, with the cauda, cornicles and 

 the greater part of the rostrum, 

 antenna? and legs black. The head 

 is marked with two longitudinal 



dark bands, and the abdomen with a row of black spots 

 on each side and a black patch about the base of the cornicles. 

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

 . . . The winged form is somewhat different in color, the head 

 being black and the thorax chiefly black above. The abdomen 

 is pale green, bluish at the sides, with two transverse black bands 

 preceding the cauda, and the segments behind it edged with dark." 

 These differences between this and the root aphis are shown in 

 the accompanying figures. "Aphis maidis has been reported 

 at various times as a corn insect from New York to Texas, 

 Minnesota and California. The species makes its appearance 



FIG. 125. The wingless 

 female of the corn leaf- 

 aphis much enlarged. 

 (After Webster, U.S. Dept. 

 Agr.) 



