INSECTS INJURIOUS TO PEACH, PLUM AND CHERRY 587 



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 . . . Light sandy soils are worst infested, though 

 they have been found in abundance on stiff clay soils. " (Quain- 

 tance, I.e.). 



Control. The roots of young trees suspected of being affected 

 should be carefully examined and if aphids 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 

 aphids 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. 518) are suggested. When the aphids appear on the 

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

 trees are observed for their appearance, for they are very grega- 

 rious, 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 aphids may be killed by 

 spraying them with tobacco extract. 



The Green Peach-aphis * 



This aphid is a European species which has long been known 

 as a pest of peach foliage in this country, where it has become 

 widely distributed. Considerable interest attaches to the species, 

 as it furnishes a striking example of the summer migration of 

 aphids to different food-plants, and a consequent difference 

 in appearance in form and color. During the summer this species 

 feeds upon various vegetables and succulent plants, and is so 

 different in color and form that it has been well known not only 

 as a separate species, but as belonging to a distinct genus. Con- 

 cerning its injury to the peach, E. P. Taylor states: " The 

 peach-growers of Western Colorado have suffered loss from it, 

 from its heavy infestation of the leaves of the trees in the spring, 



