CONTRIBUTIONS ON THE CORN ROOT-APHIS. 109 



Many of the planters report that cotton is more seriously injured 

 when it is planted after corn. This is because the root-aphis can feed 

 on the roots of corn all summer and also because the cornfields are 

 not kept clear of the wild food plants of this insect. For this reason 

 the aphides can find an abundant food supply in the cornfields all 

 summer. In cornfields as far south as Salisbury, N. C, the eggs of 

 this aphis are laid on the roots of late replanted or scrub corn which 

 was left uncut, or more often, perhaps, on the roots of its wild food 

 plants. These eggs are then taken into the burrows of the ants and 

 cared for by them during the winter. When these eggs hatch in the 

 spring, the young larvae are placed by the ants on the roots of cotton 

 or corn, if these crops are up ; if not, they are placed on weed roots 

 and live there for a while, and most of them are transferred to the 

 roots of corn and cotton as soon as these plants become available. 



If corn is to be followed by cotton, it will be best to plow the land 

 as early as possible in the fall and to sow to a cover crop later. This 

 will prevent the eggs of the root-aphis from being laid in the field, 

 while the plowing and cultivation will break up the nests of the ants 

 and prevent them from caring for the eggs that are laid. The 

 borders of the field should be kept as clear of weeds as possible. 



INJURY TO ASTERS. 



The first record Ave have found regarding the injury of a root- 

 aphis to the Chinese or German aster is in an article on " The culture 

 of the aster," b}^ Edward S. Rand, a in which he says : 



The earth should not be sandy, as in such soil they are very subject to the 

 attacks of a root-aphis, which always proves fatal to the plant. 



And again: 



For the root-aphis which troubles the plant in sandy soils we know of no 

 remedy but to dig up the affected plant and destroy the insect. 



From this it appears that the root-aphis was well known as a 

 serious enemy of the aster in New England as early as 1858, or only 

 about thirteen years after the China aster became numerous there. 

 A later record is found in the Practical Farmer for 1875, an extract of 

 which is given in the Horticulturist and Journal of Rural Art and 

 Taste, b where mention is made of the " dusty louse " which " is found 

 at the roots of German asters in hot, dry weather." Watering the 

 asters heavily is mentioned as a remedy. 



The first record in the files of the Bureau of Entomology in regard 

 to this pest on asters is an inquiry from Washington, D. C, in July, 

 1899. Since then inquiries have come from the following States: 



a Trans. Mass. Hort. Soc. f. 1858,, pp. 26, 27. 



& Horticulturist and Journal of Rural Art and Taste, vol. 30, p. 366, 1875. 



