40 ASSOCIATION OF ECONOMIC ENTOMOLOGISTS. 



Mr. Sanborn asked what relation the migratory form of this aphis 

 has to the infestation of new fields. If it is necessary for the aphis to 

 be cared for by ants, it would seem as if the chance of its being found 

 when migrating into a new field would be slight. 



Mr. Forbes said that ants are such great explorers that the chance 

 was not so small as might appear. 



Mr. Sanborn asked how far the aphis flew. 



Mr. Forbes said that he did not know exactly ; it depended on the 

 strength of the wind. 



Mr. Webster stated that Professor Sajo had called attention to the 

 fact that many insects like the aphides would climb to some elevated 

 object, like a stem of grass, and deliberately give themselves to the 

 wind to be carried away by it, perhaps for long distances. He had 

 himself observed that the ants seemed to be always on the watch for 

 the aphis in the cornfields. While he was familiar with the experi- 

 ments and results obtained by Doctor Forbes, he would like very 

 much to see how they would work out in the hilly country of the 

 South. The corn root-aphis had during the past summer been re- 

 ported as very injurious in some parts of Virginia, where farmers 

 did not seem at all familiar with it, and he wondered if these cultural 

 methods would apply there as well as in the prairie country of 

 Illinois. He had many times noted that where a field previously in 

 corn had been plowed in spring and sown to oats there would be an 

 occasional ear missed at husking that when plowed under would 

 send up a cluster of young plants, and the roots of these would be 

 infested by the root -aphides, attended b}^ ants. He expressed the hope 

 that Doctor Forbes would experiment with fertilizing ground with 

 barnyard manure as a possible repellent, as he had observed that in 

 portions of fields where this manure had been applied before plowing 

 there were fewer root-aphides. 



Mr. Osborn called attention to the fact that since the aphis can not 

 exist without the ant, we have here a condition in some ways analo- 

 gous to parasitism. 



]SIr. Sanderson called attention to the fact that in the case of the 

 strawberry root-aphis {Aphis forhesn Weed) the eggs are laid upon 

 the stems and foliage of the plant and are not cared for by the ants, 

 but that the ants are entirely responsible for carrying the aphides down 

 u])()n the roots of the plants in the spring, for tunneling around the 

 roots of the plants, and very largely for carrying the aphides from 

 plant to plant and thus spreading the pest. This would seem to be 

 a transitional stage in the care of aphides given by ants from that 

 given the aerial species to that afforded the corn root-aphis. A^^lat 

 is the percentage of migrants to wingless insects in the corn root- 

 aphis ? 



