140 FARM SPIES 



"That is the same old question asked over and 

 over again until it is almost worn out. We have 

 tried everything we could think of, hoping that we 

 might be able to kill them in the soil or drive them 

 away from the plants. Among the many things ex- 

 perimented with none has so far proven effective. 

 We have made up our minds that the only remedy 

 so far known is hard sensible farming. That, we 

 know, does control them. 



"The first step is to keep. the aphids off the 

 field for at least one year, or, in other words, drive 

 them away from the field." 



"How can you do that?" several exclaimed. 



The entomologist continued: "We have studied 

 the food-plants and we know quite well on which 

 plants the aphids can live and also those on which 

 they cannot live. For this reason we keep their 

 food-plants off the field which is to be planted in 

 cotton ; this forces them to leave and allows the 

 cotton to get a good start before enough aphids can 

 be brought back to harm the plants. It will never 

 do to let your land, on which you wish to plant 

 cotton, lie idle during the winter, because that gives 

 the wild food-plants a chance to grow on such land, 

 and I have already explained to you how well the 

 ants know how to make use of them." 



"What are some of those wild food-plants you 

 are talking about?" several farmers asked. 



