THE COTTON ROOT-LOUSE 143 



the aphids dp not feed on oats, the ants would not 

 care to keep them there just to starve. If the ants 

 figure on getting into the field after the oats are 

 harvested they are badly mistaken, because the oats 

 are followed by cowpeas, which is not a food-plant 

 for the aphids. To make matters still worse for the 

 ants and aphids, you follow the cowpeas with oats, 

 rye, vetch, or clover for winter cover; as none of 

 these is a food-plant there will be few aphids on 

 that field by spring. Then is the time to plant the 

 field in cotton." 



"Why not plant that field in corn?" one farmer 

 asked. 



"Because," answered the entomologist, "there is 

 no crop on the farm that suffers so much from these 

 aphids as cotton, and for that reason you should 

 give cotton the first chance after the field is clean." 



"In regard to cultivation," the entomologist 

 continued, "as soon as the cotton is large enough, 

 begin and give it frequent shallow cultivation until 

 the plants have a good start. This cultivation nettles 

 the ants very much because they do not go by sight 

 as you or I do, but they seem to go from one place 

 to another by following trails made before. Just 

 think, Mr. Gardner, if you were an ant and wished 

 to go home you would have to follow some trail 

 you made when you came to the field before, instead 

 of looking and seeing your house and then walking 



