20 The Bulletin. 



Injury in North Carolina. — In this State this Root-louse has not often 

 been reported on corn, though it does injury to this crop. It is much 

 more often reported as a pest of cotton, and the writer believes that the 

 first published record of it as a really serious cotton pest was in a Bulle- 

 tin of this Department.^ Injury to corn, however, has been reported 

 several times in recent years, from the counties of Bladen, Caldwell, For- 

 syth, Gaston, and Union. As it is a pest of cotton chiefly in our eastern 

 counties, has been reported on corn to the edge of the mountains, and is 

 known as a corn pest throughout the entire State of Illinois, we must 

 conclude that it does attack corn throughout the entire length and 

 breadth of North Carolina, even though definite complaints of it on this 

 crop have been few. Like the other underground insects, it is likely to 

 pass unnoticed except in the most aggravated cases. 



Life-history. — Here again we must acknowledge our indebtedness to 

 the work of Dr. Forbes in Illinois. ISTot only was he the original de- 

 scriber of the Corn Root-louse as a species, but what is known of its ex- 

 act life-history comes largely from the work of his office. Working 

 in a great State the chief crop of which is corn, he has studied care- 

 fully the insect enemies of that plant, and many of his publications 

 have discussed this Corn Root-louse, and the relation which the attend- 

 ant ant bears to it. 



Dr. Forbes says that the first generation of Root-lice in the spring 

 are all wingless, and if the plants on which they feed remain thrifty, 

 many generations in succession will be wingless; but that if the plant 

 becomes overcrowded by them and seems likely to die, then many of 

 the oncoming generations have wings which enable them to migrate in 

 search of new plants. Such stray lice are found by the ants which 

 attend them, and are quickly placed on roots of plants which will sup- 

 port them — on corn if in a cornfield. Here they multiply until the ap- 

 proach of winter. All this time, from the opening of spring through 

 many generations, only female Root-lice are produced, all being born 

 alive (no eggs) ; but as cold weather approaches in fall, the last gen- 

 eration contains both males and females; these mate, and the fertilized 

 females lay eggs which pass the winter and hatch to wingless females in 

 the spring. In Illinois Dr. Forbes finds an average of about sixteen gen- 

 erations per year.2 The louse is largely dependent upon the cornfield 

 ant, for this ant stores the eggs of the Root-louse in its burrows over 

 winter, and when they hatch in spring they place the young lice on 

 the roots of plants upon which they can feed. The lice secrete from 

 their bodies a sweetish substance known as "honey-dew," and it is to 

 obtain this that the ants attend the lice. The ants themselves do not 

 hurt the corn (or cotton), nor do they give birth to lice, nor do they de- 



iVol. 20. No. R. Bui. N. C. Dept. Agr., June, 1908, "Insect Enemies of Cotton," by 

 P. Sherman, p. 17. 



^Account condensed from "The Corn Root-aphis in Illinois." Circular of III. Exp. Sta., 

 Jan., 1913, by S. A. Forbes. 



