170 INSECT PESTS OF FARM, GARDEN AND ORCHARD 



The Corn Leaf -aphis * 



Although the corn leaf-aphis is not often very seriously 

 injurious to corn, in Texas and other Southern States it frequently 

 becomes so abundant on sorghum and corn, and in winter on 

 barley, as to do considerable injury. This species is also of interest 

 in that it appears on corn foliage in midsummer at the time when 

 the numbers of the root-aphis commence to decrease on the roots, 



FIG. 124. The corn leaf-aphis (Aphis maidis Fitch) : winged female much 

 enlarged. (After Webster, U. S. Dept. Agr.) 



and it was for many years thought to be the same species. Care- 

 ful rearing experiments made under the direction of Dr. S. A. 

 Forbes have failed to show any connection between the root- 

 aphis and leaf-aphis, the aphides from the roots being unable to 

 establish themselves on the leaves and those on the leaves never 

 migrating to the roots. f 



Dr. Forbes describes the species in his twenty-third report 

 as follows: " In the latter part of the summer this bluish-green 

 plant-louse may occasionally be found on the younger leaves, 



* Aphis maidis Fitch. Family Aphididoe. See Webster and Davis, 

 I.e., p. 164. 



t S. A. Forbes, 13th, 16th, 18th, and 23d Reports of the State Entomologist 

 of Illinois. 



