46 THE MONTHLY BULLETIN. 



form. Of the species named above, two stand out as splendid examples 

 of the subterranean form. They are woolly aphis and the black peach 

 aphis, but both of these have aerial generations. The beet aphis {Pem- 

 phigiis hetce Doane) and {Trifidaplns radicicola Essig) are not known 

 to be other than strictly subterranean in their habits. In considering 

 methods of control we shall take the woolly aphis {Eriosoma lanigera 

 Hausm.) as an example. 



Methods for Controlling Underground Forms. 



Prevention. In setting out a young orchard one of the first things 

 to consider is how to prevent the introduction of certain serious pests 

 and diseases which may be carried on nursery stock. Both the peach 

 aphis and the woolly aphis are easily distributed on young trees. The 

 following precautions should be taken in setting out any new apple or 

 peach orchard : 



1. Set out clean stock. Do not buy trees which have the roots puddled 

 unless the mud is washed off — it may hide the woolly aphis or black 

 peach aphis and such infested trees would be severely handicapped and 

 are not worth planting. 



2. Woolly aphis does very little damage to the Northern Spy; espe- 

 cially is this true regarding the attacks on the roots, therefore, if possi- 

 ble, buy apple trees grafted on Northern Spy roots, if your section is 

 troubled with the woolly aphis. 



3. Set trees fairly deep, keep soil thoroughly cultivated so as to get 

 roots down as far as possible. The woolly aphis seldom works lower 

 than ten (10) inches below the surface. 



Sprays. Before making applications around the crown of the tree 

 for the controlling of root forms, first remove earth around the roots to 

 a depth of six or seven inches and a distance of two or three feet from 

 the crown. Use two or three gallons of liquid per tree, spraying 

 thoroughly on exposed roots. When the liquid is nearly all soaked into 

 the soil cover up the basin. The sprays which have given the most 

 satisfaction in these cases are as follows: 



Tobacco Leaves. A large number of tobacco leaves placed around 

 the roots of the trees in the fall will do much to keep out underground 

 lice. 



Tobacco Decoction. Tobacco stems, dust or waste, 2 pounds ; water, 

 3 gallons. Steep tobacco stems in water for at least one hour before 

 applying. If whole leaf tobacco is used, 1 pound is sufficient for 3 

 gallons of water. 



Black Leaf. Black leaf in proportions of 1 to 70 of water is also 

 effective on the root forms. 



Tanglefoot. If the dormant trees are sprayed with a strong solution 

 of kerosene emulsion or lime-sulphur just before the buds open in the 

 spring, it is well to put a tangle-foot band around the trunk of the tree 

 to keep root forms from migrating to the top. In order to prevent 

 injury to the tree the tangle-foot is smeared on heavy joaper, which is 



