204 



APPLIED ENTOMOLOGY 



The eggs of this aphid hatch early in spring and from 10 to 22 generations 

 (Figs. 196 and 197) are produced during the season. As cool fall weather 

 appears, a generation of sexual individuals (Fig. 198) appears and these lay 

 eggs which pass the winter. During this season they may be found in the 

 ground in nests of several kinds of ants but most 

 frequently in those of the little brown ant, Lasius niger 

 americanus. They are oval, black and glistening and 

 are sometimes found in small piles in the nests of the 

 ants. In cold weather the ants carry the eggs down 

 below the frost and on warm days bring them up to 

 warmer levels. In spring, when various weeds such as 

 smartweed, begin to grow, the ants tunnel along the 

 roots of these weeds and place the young lice as they 

 hatch, on them to feed. Later, when corn roots 

 become available the ants transfer the lice to them, 

 where they and their descendants feed during the rest 

 of the season. Winged migrants are produced after a 

 generation or two and these individuals spreading, are 

 taken to corn roots by ants which may find them. All 

 summer and fall the ants care for the lice, taking them 

 from one plant to another and collecting from them the 

 honey-dew upon which the ants feed. In the fall when 

 the eggs are laid these are gathered by the ants and 

 stored in their nests over winter. 

 Where the Corn Root Aphid is abundant it becomes a serious corn pest, 

 dwarfing the corn and turning the leaves yellow or reddish and sometimes destroy- 

 ing the plants, particularly when weather conditions are also unfavorable. 



Fig. 196.— Corn Root 

 Aphis (Aphis maidi- 

 radicis Forbes) ; wingless, 

 viviparous female. 

 Greatly enlarged. {From 

 U. S. D. A. Bur. Ent. 

 Bull. 85, Part VL) 



Fig. 197. — Winged, viviparous female of the Corn Root Aphis, greatly enlarged. 

 U. S. D. A. Bur. Ent. Bull. 85, Part VI.) 



{From 



Control. — Rotation of crops is of much value as a control, for as the lice 

 cannot migrate until their second generation, corn planted on land where they 

 are not already present will get well started. Fertilization and frequent cultiva- 



