INSECTS INJURIOUS TO STONE FRUITS 657 



from tree to tree and from the roots to the leaves and back. 

 " During summer the aphides for the most part are to be found 

 on the roots, though a few may be found on the foliage and the 

 shoots in badly infested orchards at almost any time during the 

 growing season. Below ground they occur promiscuously on 

 roots of all sizes, but the smaller and more tender ones are pre- 

 ferred. Some of the aphides may retain their hold on the roots 

 after the trees are dug, and the insect is thus frequently distributed 

 on nursery stock. . . . Light sandy soils are worst infested, 

 though they have been fo'md in abundance on stiff clay soils." 

 (Quaintance, I.e.). Neither the true sexual forms nor the 

 eggs of this species have ever been observed, and there is 

 room for a much better knowledge of its life history. It is 

 stated by some writers that the aphides migrate to the roots 

 in the fall. 



Control. The roots of young trees suspected of being affected 

 should be carefully examined and if aphides are found they should 

 be dipped in strong tobacco water. Nurserymen prevent injury 

 by making liberal applications of tobacco dust in the trench and 

 along the rows. Tobacco dust may also be used against the 

 aphides on the roots of orchard trees by removing the surface 

 soil and applying a liberal dressing of the dust, which will be 

 leached down on to the roots by the rains. It should be applied 

 over the smaller roots. The treatment for the root forms has 

 not been sufficiently studied to warrant any conclusions as to 

 satisfactory methods, but the same as advised for the woolly apple- 

 aphis (p. 587) are suggested. When the aphides appear on the 

 young shoots in the spring they may be readily controlled if the 

 trees are observed for their appearance, for they are veiy gregar- 

 ious, clustering on one shoot until it is well covered before spread- 

 ing to the rest of a tree, and becoming abundant on it before 

 spreading to others. Often the small infested shoots may simply 

 be broken off and destroyed. The aphides may be killed by 

 spraying them with ken^ne emulsion, 15 per cent kerosene, 

 tobacco extracts or whale-oil soap, 1 pound to 4 gallons. The 

 spray should be applied with force so as to penetrate the houey- 



