46 



A SECOND CONTEIBUTION TO THE LIFE HISTORY OF THE 

 CORN PLANT LOUSE {Aphis niaidis, Fitch.) 



By H. GARMAN. 



In continuing the study of the life history of the corn plant 

 louse, at the beginning of the summer of 1885 a large frame was 

 erected out of doors and so enclosed as to exclude insects from 

 ■without and to prevent those within from escaping. In this en- 

 closed frame three hills of field corn were planted and on their ap- 

 pearance above ground one of them was stocked with a colony of 

 Lasius alienus, Forst.,* the small ant which habitually attends the 

 root form of this plant louse. The ants made themselves quar- 

 ters about the roots of the corn, and on the 19th of July a number 

 of wingless viviparous female lice, with their young and one pupa, 

 were placed within reach of the ants and were at once carried 

 to the roots of the corn by the latter. On the 22d of July other root 

 lice, wingless and winged, were placed near the stocked plants and 

 were also carried to the roots. 



With a view to learning whether or not root lice would of them- 

 selves make their way to the roots of corn, on July 22d and subse- 

 quently many specimens were placed at the base of one of the hills 

 not colonized with ants. They always disappeared, but could not 

 be found afterwards on the roots. The plants with which they were 

 placed continued to grow as well as the third hill under cover, 

 which from the first had not been disturbed, and at the close of 

 the summer careful search did not disclose lice on the roots. 



The injurious effect of the lice on the infested plants was soon 

 noticeable in their smaller size and less vigorous growth. At 

 various times during the summer the burrows of the ants along the 

 roots were uncovered, revealing each time the presence of lice. 

 From July 23d until the first of August winged lice came from these 

 burrows and were sometimes found on the blades of corn, but more 

 frequently on the inside of the enclosing cloth of the frame. These 

 winged individuals showed no disposition to establish colonies on 

 the blades of corn, but on the contrary seemed desirous of leaving 

 the plants as soon as possible. All were viviparous females and in 



*This species has boenPheretofore mentioned in these reports as Lasins flaws, on the 

 strength of a rletermination madefor us in 1882 by a distinguished student of American 

 Formieidas. Doubts arising as to the correctness of this specific name, especially as the 

 habits of our species were very different from those of i. fiaeus as reported in the old 

 world, specimens were sent, in 1885, to Dr. Aug. Forel. of Geneva, Switzerland, and the 

 name here given rests on his aiithority.— S. A. F.l 



