stock. The insect is known also from Japan. In our own country, 

 while not usually a serious pest, it is said to damage corn, sorghum, 

 and barley in Texas, while Doctor Forbes has noted a reddish dis- 

 coloration duo, he thinks, to a bacterial effect following its occurrence 

 on broom corn. 



ArPEARANCE AND HABITS. 



The corn leaf -aphis is bluish green in color. It appears on corn 

 throughout the Middle West early in July — about the time that the 

 root-aphis begins to decrease in numbers on the roots — sometimes 

 literall}^ swarming on the leaves, husks, and tassels. Here it gives 

 birth to its young, and disappears from the plants only as these ripen 

 and become dr} , some individuals even remaining among the husks of 

 belated ears until freezing weather kills them outright. 



Whence these insects come, in July, when the first few winged 

 females appear on the leaves of the corn, is a mystery, eqiudod onlv 



Fig. 1. — The forii le;if-aphis {Aplih innidis): Winged female. Mueh enlarged (original"). 



b}" the problem as to the destination of the winged individuals that 

 leave the same plants in autumn. While on the plants they are 

 attended ])y the little brown ant, the same one that cares for the root- 

 aphis. Thus it will be seen that we have but a fragment of the life 

 cycle of this insect; for, if it is a distinct species, it must occur else- 

 where than on corn long before July, and it is equally clear that if 

 distinct it must migrate in the fall to some plant that will afiord food 

 for the ,young the following spring, there to deposit its eggs. We 

 judge this to be the case, as it is known that with most species of 

 aphides there occurs in fall a generation of winged females that 11}^ 

 to the spring food-|)lant, there to produce a generation of both males 

 and females, the latter laying eggs that do not hatch until spring. 

 From spring until fall there are no males and no eggs; all young 



[Cir.86J 



