212 Illinois State Lahoratorij of Natural History. 



were almost immediately carried below. A gauze-covered 

 frame was placed over the plants. July 5 the leaves of the 

 plants were examined for at^rial corn lice, but none were found. 

 The frame was replaced and was not again taken ofE until 

 October 20, when the leaves of the plants were carefully exam- 

 ined for aphides, but no traces of them were found. On the 

 roots, however, there were numbers of oviparous com lice with 

 a few wingless viviparous ones and several males — a form 

 which had never before been discovered. There was also a 

 single winged viviparous root louse and a pupa of the same form. 

 All were put in a watch glass over night, and the next morning 

 one of the males was observed in copula with an oviparous 

 female, thus establishing the sex of the former beyond a doubt. 

 The pupa had also moulted and become a winged louse: and 

 several of the oviparous females had laid yellow eggs. The 

 fully developed oviparous forms were mostly of a peculiar yel- 

 lowish pink color, probably due partially at least to the eggs 

 within the abdomen. Many of the young lice in this corn hill 

 were sucking the juices from the roots, which still had a little 

 sap left in them; but most of the adults were wandering about 

 in the galleries of the ant colony. • 



This experiment proved beyond reasonable doubt that the 

 life cycle of the root form of Aphis maidis can be completed 

 without the appearance of the aerial form. To determine 

 whether there ever is any connection between the two forms 

 will require more work. 



Summary. 



Assuming for the present that there is no connection 

 between the root and aerial forms of Aphis maidis, we are justi- 

 lied in the light of these observations in summarizing the life 

 history of the former as follows (starting with the hibernating 

 eggs in the nests of ants): 



Daring the first warm days of spring, usually before the 

 ground is plowed, there hatch from the eggs small greenish lice 

 that are transferred by the ants to the roots and radicles of Se- 

 taria and Polygonum, where they are carefully tended by the 

 ants. In about a fortnight these young have become adult stem- 

 mothers ('"'Pseudof/i/iui fiindafri.r'" ) and give l)irth to (juite a 



