232 



CORN 



guished from the grass louse, which is white with a blackish head, 

 there being no appearance of green. The eggs are laid in the fall 

 and the ants store them away over winter. The first hatching gen- 

 era.lly takes place in the spring before the corn is planted, the young 

 living for a time on the roots of weeds which are laid bare by the 

 ants. Smartweed is especially liked by the young aphids. As soon 

 as the young corn plant starts, the ants immediately remove the aphids 

 from the roots of the weeds to the corn roots. The ants have been 

 known to burrow hills of corn in advance and seize the winged aphids 

 that would happen that way and bear them to their subterranean home 

 on the roots of the corn plant. The first generation of the corn-root 

 aphis is wingless, and is therefore confined to fields previously in 

 corn. This and succeeding generations are asexual giving birth to the 

 living young. The second generation consists both of winged and wing- 

 less aphids. The winged aphids may travel to other fields, but they 

 generally do not become sufficiently numerous to affect a field not in 

 corn the previous year. It is generally November before those of the 

 viviparious generation (those producing living young) are all dead. Af- 

 ter this time the sexual generation is presented. These lay the eggs in 

 the late fall ready for the ants to store away. In the spring the 

 above outlined life history is repeated. It is estimated that each 

 female will give birth to 12 or 15 young, although the life period 

 of the first three generations is but 19 days. There are some 10 to 16 

 generations in one season. 



The apparently disinterested guardianship of the ants is not en- 

 tirely without profit. The aphis has been termed the "ant's cow," due 

 to the fact that it excretes a sweet liquid called "honey dew" through 

 the two small tubular projections situated on each side of the back 

 near the caudal end. The ants are very fond of this liquid, which they 

 obtain by tapping the aphids lightly on the back. The presence of 

 ants about a hill of corn almost always means that the aphids are at 

 work on the roots of the plant. 



Prevention and Remedy. Mo other crop is particularly Ifable to be 

 injured by the corn-root aphis, with the exception, possibly, of broom 

 corn and sorghum. An instance has been noted in Kansas where 

 sorghum was badly infested. A rotation of crops is the only method 

 by which a field can be relieved from the serious attacks of this pest. 

 Inasmuch as no crops following corn are seriously injured by the 

 lice there need be no fear in plowing up infested corn ground and 

 sowing to some other cereal. Fall plowing and early spring plowing 

 disturbs the homes of the ants and destroys large quantities of eggs 

 of the aphis. Clean cultivation, especially on low ground, prevents 



